The major topography is that of folded complex mountains along the north-south oriented, part of Tanaosi Mountain range. There are only a few plains. The altitude is between 100 and 1,249 meters above sea level. Khao Chang Phueak is the highest summit located in the west. Major summits are Khao Chang Phueak, Khao Nisa, Khao Phu Thong, Khao Dang, Khao Pak Pratu, Khao Lo Lo, Khao Pra Nong Tho Khi, and Khao Cha Long. It is the catchment are for many waterways such as Malai Creek, Kop Creek, San Creek, Ong Phra Creek, Pi Khi Creek, Pak Khok Creek, and Chet Mit Creek by flowing into the eastern plains into Khao Laem Dam. Other creeks flow into Khwae Noi River.

    This area is influenced by tropical monsoon. Summer is from February to April, rainy season runs from May to July, and winter lasts from November to January.

      Thong Pha Phum National Park is part of the western forest with its original natural stage. The forest types can be divided into 4 categories: 
     1) Tropical Rain Forest, which is the home to a number of significant plant species, including Iron Wood, Resin Tree, Dipterocarpus grandiflorus (Blanco), Parashorea stellata Kurz, Resak Tembaga, Tembusu, Champak, Monkey Jack, Djenkol Bean Fruit. The ground plants include Rattan, Fern, Pandanus , and palm.
      2) Dry Evergreen Forest plants include Resin Tree, Dipterocarpus turbinatus C.F. Gaertn., Iron Wood, Moulmein Cedar, Magnolia baillonii Pierre, Mesawa, Mangifera caloneura Kurz, Protium serratum Engl., Baccaurea ramiflora  Lour.., Burmese grape, and Tetrameles nudiflora R.Br. The ground plants include Palm, Galanga, and Various ferns.
       3) Hill Evergreen Forest includes various types of Evergreen Chinkapin, Birch, Manglietia garrettii Cralb, Paldao,  Sumastra Benzoin, Cinnamon, Needle wood, and ground plants such as mosses, and various ferns.
       4) Mixed Deciduous Forest contains the most important plant species, with essential plant species such as Burma Padauk, Iron Wood, Lagerstroemia calyculata, Thai Bungor,  Dillenia suffruticosa, Afzelia xylocarpa (Kurz) Craib, Queen's Flower, Duabanga grandiflora (DC.) Walp., Schleichera oleosa, Garuga pinnata, Yellow Millettia Wood, Diospyros mollis Griff, Vitex peduncularis Wall. ex Schauer, Beleric Myrobalan, Irvingia malayana, and Spondias pinnata. Ground plants include Gigantochloa albociliata Munro, Dendrocalamus strictus, Bambusa nutans Wall, Tinwa Bamboo, Bambusa bambos (L.) Voss, and Teasel.

           Due to its proximity to Myanmar, Thong Pha Phum National Park is home to a variety of wildlife, which migrate between the countries on a regular basis. The  forest is sparsely populated and the wildlife is fairly undisturbed. Regular appearances include Asian Elephants, Serows, Deer, Barking Deer, Mouse Deer, Wild Boars, Bears, Monkeys, Langurs, Sunda Flying Lemurs, Gibbons, Common Palm Civet, Civet, Fishing Cats, Clouded Leopards, Tigers, Malayan Sun Bear, Asian black bear, Pteromyini,  Premna herbacea Roxb , Mus musculus , Mongoose, Bat, Burmese Hare , Wild Cat, Dhole, and Porcupine. There is also lots of birdlife including Hornbill, Swallow, Falcon, Grey Heron , Eagle, Owl, Bulbul, Black-Crowned Night Heron, Asian Barred Owlet, Barn Owl, Greater Coucals, Mynas, Oriental Magpie Robin, Oriole, Scaly-Breasted  Partridge, White-breasted Waterhen, Hill Myna, Drongo, Woodpecker, Western Koel, Eastern Jungle Crow and Red Junglefowl , Red Junglefowl . Reptiles include Tree Lizard, Gecko, Flying Lizard, Skink, Butterfly Lizard, Centipede, Scorpiones, Millipede, Leech,, Leeches, Asiatic Softshell Turtle, Frogs, Puddle Frog, Toads, Chubby Frog, Tor tambroides, Minnow, Red-tailed Snakehead , Striped Snakehead, Eel,  Armed Spiny eel, Silver Barb , Climbing Perch, Mystus micracathus, and Giant Snake-Head Fish.