Khun Nan National Park covers the areas of Bor Gleur District of Nan Province within an approximate area of 246.37 square kilometers or approximately 153,982 rai. The National Park is situated in the area of Pa Doi Phu Kha and Pa Pha Daeng National Conserved Forest in Tambol Phobphra, Tambol Bor Gleur Tai, and Tambol Dongphaya of Bor Gleur District, Nan Province.

The geographical features of the National Park consist of high mountains in 1A Level upstream areas and having the watershed on the highest mountaintop situated in Tambon Dongphaya. Major mountains in the area include Phu Fa Mountains, Khun Namwahnoi Mountains, Namwahklang Mountains, and Pi Pun Mountains. Namwah River, originated from the watershed mountains, is a large and significant river flowing across the areas southwards.

Temperatures in the National Park are between 1-7 C in winter and between 28-33„aC in summer. Since the National Park consists of forests and being surrounded by mountains and far away from communities and big cities, therefore, the weather at the National Park is fresh, clear, and purified throughout the year.