Doi Wiang Pha is to be announced as a national park covering the areas of Mae Fang National Conserved Forest in Tambol Sridongyen, Tambol Maetalob, Chaiprakarn District, Tambol Mae Kha, Tambol Mae Kha, Fang District, Chiang Mai Province, and the left side of Mae Lao National Conserved Forest in Tambol Pa Daed, Tambol Srithoi, Tambol Thakor of Chiang Rai Province within an approximate area of 583 square kilometers or 364,375 rai.

Topography
The geographical features of the National Park consist of high mountains, extending northwards, which are regarded as the boundary between Chiang Mai and Chiang Rai provinces. Doi Wiang Pha is the highest mountain of the National Park, at the altitude of 1,834 meters above the medium sea level. Most of the areas are water-source forests for major gullies, particularly Fang River and branches of Lao River such as Mae Fangluang Gully, Mae Fangnoi Gully, Yangmin River, etc.

Climate
The weather at the National Park can be divided into 3 seasons including rainy season (May-October), when it rains heavily in September, winter (November-February), when the weather is cool and ideal for travelling, and summer (March-April), when the weather is rather hot.

Flora and Fauna
There are a variety of forests covering the whole areas of the National Park, including virgin forests, arid, evergreen forests, pinery, timber forests, and mixed forests, depending on the altitude of the areas. Major plants include teak, rubber trees, Leguminosae (Pradoo), Michelia Alba, Pinus Merkusii Jungh (two-leaf pines), different kinds of Lithocarpus Cantleyanus (Kor), moss, ferns, orchids, etc.

Due to its abundance of forests, varieties of plants, and different altitudes of the areas (300-1,834 meters), the National Park has become the source of foods and dwelling places for different kinds of wild animals including Muntiacus Muntjak, wild boars, gorals, porcupines, wild rabbits, monkeys, masked palm civets, squirrels, tree shrews, and different kinds of birds such as White-rumped Shama, turtle doves, hawks, while fowls, etc.