The park is the third largest in Thailand. It covers an area of 2,168 square kilometers, including tropical seasonal forests and grasslands. Elevations mostly range from . There are 3,000 species of plants, 320 species of birds like red junglefowl and coral-billed ground cuckoo, and 66 species of mammals, including Asian black bear, Indian elephant, gaur, gibbon, Indian sambar deer, southern pig-tailed macaque, Indian muntjac, Ussuri dhole, and wild pig. There are no tigers in Khao Yai, and there have not been any for at least 20 years. Its waterfalls include the Heo Narok (เหวนรก), and Heo Suwat (หวสุวัต) made famous from the film "The Beach".