Phu Sang National Park located in Phu Sang District, Phayao province and Thoeng District, Chiang Rai province. The 284.8 km2 Park is watershed of many streams in Phayao, comprises of hill evergreen, deciduous and dipterocarp forest.

The are consists of mountain range, about 440-1,548 meters above sea level, close to the border of Lao, is the source of water of Lao River, Ngao River, Puea River, Bong River and Yuan River, which go to maintain the plantation of Chiang Kham District.

There are three seasons in Phu Sang National Park.
Rainy season – from May to October
Winter – from November to January
Summer – from February to April

The forest consists of semi-evergreen forest, mixed forest and montane forest. And the plants are Yang, wild champak, Malabar ironwood, baleric myrobalan, cinnamon tree, pine, Heang (a kind of Dipterocarpus obtusifolius), eng, Burmese ebony, ironwood, Tabak (a kind of Lagerstroemia), Ceylon Oak, Teak wood, Sela (a kind of Lagerstroemia), Chittagong wood, ingyin, Siamese sal, myobalan wood, wild mango, Makhaa mong, many kinds of bamboo and grass, etc. The animals found are mountain goat, deer, barking deer, mouse deer, monkey, wild boar, langur, hare, wild cat, porcupine, palm civet, civet, squirrel, Asiatic wild dog, and many kinds of birds.