[2] Khao Yai National Park is in the western part of the Sankamphaeng Mountain Range, at the southwestern boundary of the Khorat Plateau.

It covers an area of 1,353,472 rai ~ 2,166 km2 (836 sq mi),[3] including tropical seasonal forests and grasslands.

The area was formally recognized by the government and classified as Tambon Khao Yai within Pak Phli District.

After an attempt to capture the suspects in the area, in 1932 the villagers were relocated into the plains some 30 km away and the tambon status was cancelled.

A major role in its establishment was played by Boonsong Lekakul, one of the 20th century's most famous Thai conservationists.

With such difficult challenges climbing the mountain, The Lottery Club once awarded a 60,000 baht prize to a woman who would conquer the summit of the peak.

[6] During one of its busiest periods, New Year's week from 30 December – 3 January 2016, the park received 156,574 visitors.

The Lam Takhong River drains from the central Khao Yai area and runs in a northeasterly direction to the Mekong.

The Sai Yai River system drains from the eastern basin, turning sharply into the southern floodplains and on to the Gulf of Thailand.

The Saraburi Province drainage system drains westward from the far west of Khao Yai.

[10] In early-2017 it was announced that 18 tigers, including five males, seven female and six cubs, were filmed by surveillance cameras in the Dong Phaya Yen-Khao Yai world heritage site in June 2016 and February 2017 in a joint effort of the Department of National Parks, the Freeland Foundation, and the Panthera Corporation.