The rocks found in Phu Kao-Phu Phan Kham National Park are Khorat Soil Group, which originated in the Mesozoic Era about 230 million years ago, consisting of 6 rock groups as follows:

1.   Phu Phan Formation, which is white-brown pebbly sandstone. The range of grains are from medium-sized to coarse grain, mixed with gravels and good erosion resistance.

2.   Sao Khua Formation : The rock has the characteristics of slightly red sandstone. The grains are white and small. In the area where the siltstone appears, there are some gravels and the shape of the mountain is sloping.

3. Phra Wihan Formation - Most of the rocks are white and pink sandstone. The range of grains are from medium-sized to coarse.

4. Phu Kradung Formation features mostly reddish-and-magenta brown.  It contains mica and is mixed with reddish-brown siltstone.

5. Nam Phong Formation contains red and brown sandstone, mixed with a little gravel and pebbles.

6.  Khok Kruat Formation (Kkk) contains R. Coast sandstone, siltstone, mudstone, and conglomerate maroon. The colors found include purple, red, white, and brown.  The layers range from medium to thick and the grains of sedimentary rocks range from fine to medium-sized. There are rip-up clasts, and in some layers, a little gravel is found. In some areas, it is interspersed with red and reddish-brown shale and sandstone. Lime conglomerate is found on the top layer. 

The seasons of Phu Kao-Phu Phan Kham National Park are divided into 3 seasons.  Summer is between March and May and the average temperature is very high in April. The rainy season is between June and October and the rainfall is heavy during August-October. The winter is between November and February.

  - Maximum temperature is 41 degrees Celsius (during March-April of every year).

  - Minimum temperature is 12 degrees Celsius (during December and January of every year)

  - The amount of rainfall is approximately 1,295.5 cubic millimeters per year.

Unusual climatic features and weather variations cause both physical and biological effects on Phu Kao-Phu Phan Kham National Park, but no serious natural disasters except for storms at the beginning and end of the rainy season, which cause strong winds and tidal currents in the North Lake Ubol Ratana Dam. The wave ridge is about 30 cm high (dangerous for small boats). If heavy rain continues, here may be a runoff. Drainage in some areas is slow, especially on the roads, so when the water runs down the road, it's difficult to travel, especially on the gravel roads, in both the part of Phu Kao and the part of Phu Phan Kham. Moreover, it could cause large sandstone to collaps (the mountain pass in front of the national park headquarters was cut off before), causing cracks, damage, and clogging drainage channels along the roadside.

Flora and Wildlife
Plant species in Phu Kao-Phu Phan Kham National Park can be classified into 3 types of plant community as follows:
1.) Dry evergreen forest: This forest type is the most abundant in the areas of the Phu Kao-Phu Phan Kham National Park. The forest is scattered along the banks of the creek and along the banks of streams, mountainsides and valleys in some areas, the low plains between the outer rim and the inner rim which are in the northern part of the Phu Kao mountain range, around the northern area of Mu Ban Wang Mon and the inner rim around the southeastern part area of Mu Ban Dong Bak towards Phra Phutthabat Phu Kao Temple. While within the Phu Phan Kham mountain range, the dry evergreen forest is located upstream of Kum Mum creek which is on  the northeastern side of Phu Phan Kham. This dry evergreen forest covers about 10% of the Phu Kao-Phu Phan Kham National Park, consisting of important plants such as: Bungor, Hopea ferrea Laness, Dipterocarpus, Afzelia xylocarpa, Anisoptera costata, Velvet Tamarind, and various types of vines.

2.) The Mixed Deciduous Forest is located in the area that is more arid than that of the rainforest but moister than that of deciduous dipterocarp forests. The mixed deciduous forests of the Phu Kao-Phu Phan Kham National Park are found in the plain area within the inner hills of the Phu Kao part and the plains on the side of the Phu Moei hill and the outer rim of the mountains, especially the northern part of the hill, and aroundthe hillside near Phra Phutthabat Phu Kao Temple. As for the Phu Phan Kham Mountain range, small patches of mixed deciduous forest can be found in the areas with a slight slope on the side of Khon Kaen Province. The forest of this type covers an area of about 10% of the Phu Kao - Phu Phan Kham National Park, consisting of important plants such as: Xylia xylocarpa, Burma Padauk, Afzelia xylocarpa, Sindora siamensis, Irvingia malayana, Ceylon oak, Vitex pinnata, Morinda exserta Roxb., and Cotton tree, and the undergrowth plants consist of Gigantochloa albociliata Munro, Alang-alang, etc.

3.) Dry Dipterocarpus Forest: this type of forest covers most of the area in of Phu Kao – Phu Phan Kham National Park which accounts for about 70 percent of the area. The forests generally occur on hilly slopes with sandstone outcrops and on low-moisture plains. The areas in which a wide area of deciduous dipterocarp forest can be found is the mountainous area of the outer rim of the mountain and around the ridge of Phu Phan Kham Mountain range.

It consists of important plants such as: Hairy Keruing, Dipterocarpus tuberculatus Roxb., White  Meranti, Tummy-wood, Haldina cordifolia (Roxb.) Ridsdale, Creeping Lady's Sorrel, Hog Plum, Phyllanthus emblica. The undergrown plants include Cycas siamensis Miq., Arundinaria pusilia, Phoenix acaulis Ham, many types of vines, and some varieties of thorn bushes, including Melientha suavis Pierre.

In terms of wildlife, according to the present condition, There are very few animal species remaining in the area of Phu Kao-Phu Phan Kham National Park. due to the two important causes: destruction or hunting and destruction of animal habitats/habitats.

The remaining animals in the area of Phu Kao-Phu Phan Kham National Park that can be identified from their traces and from people's recounting are as follows:

1.) Mammals: "Wild Boar, many species of Civet, various types of Musk, Squirrels, many kinds of Chipmunk, various types of Wild Rats, Barking Deer, Hare, Mole, Marmot, and Loris.

2.) Birds consist of wild fowl, Peacock, Parrots, Cockatoo, many types of Doves, various types of Drongo, Dollar Roller, Wild Owls, Common Myna, many types of Woodpeckers, many types of Hawks, Lesser Whistling-Duck, Cotton Pygmy Goose, and Little Egret.

3.) Reptiles consist of: Asian Forest Tortoise, Elongated Tortoise, many types of Lizards, many types of Geckos, many types of Skinks, many types of Lizards, and many types of Snakes, both venomous and non-venomous.

4.) Amphibians consist of: Frogs, Green Paddy Frogs, Toads, and Asian painted frogs.

5.) Fish: Phu Kao-Phu Phan Kham National Park has the area of the lake above the Ubol Ratana Dam about 85 square kilometers or 53,125 rai and the creeks and streams in both the areas of the Phu Kao and the Phu Phan Kham, consisting of fish species that occur both naturally and cultured.