Heili River is located in the southwest of Ningcheng County, belonging to the Tushan branch in the seven old of Yanshan Mountains. The whole forest area is densely forested and rich in wild animals and plants, and has the reputation of "Xishuangbanna beyond the Great Wall". There are dozens of tall tree species such as pine, cypress, maple, linden, oak and birch in the reserve, accompanied by wild fruits such as wild grapes, pecans, yamanashi, apricot and jujube, and mountain treasures such as bracken, black fungus, Hericium erinaceus and yellow flowers. In particular, the natural Pinus tabulaeformis with an area of 4467 hectares is very precious and is an excellent provenance base of Pinus tabulaeformis in China. There are 777 species of wild plants, birds 1 17 and 33 species of mammals, among which Juglans mandshurica, wild soybean and Bo Huang radish 17 are national key protected plants, golden eagle, spoon chicken 18 are key protected birds, and leopards and black bears are key protected animals. In spring and summer, azaleas, peach blossoms, apricot flowers, roses, ten kinds of brocade and other flowers are colorful and dazzling. Rare birds such as pheasant, oriole, Shan Ying, bustard, lark, thrush and stork, and wild animals such as leopard, bear, wolf, fox, lynx and roe deer haunt the forest. Emperor Kangxi of the Qing Dynasty once hunted here, and there was an inscription on the stone wall across the river at Dalugou Gate.
There is a coniferous forest breeding base directly under the State Forestry Administration in Heilihe forest area, where more than a dozen tree species breed. There are also natural landscapes such as Orchid Mountain, Xianren Bridge, Sightseeing Sky and Stone Glacier in the forest area. The country-specific mountains are exquisitely carved and the stone forests alternate with each other; Xianren Bridge is a stone tunnel with a width of only one meter, with abyss on both sides. The first sight is the passage between the strange peaks and rocks, which can only squeeze one person; Stone Glacier is a relic of Quaternary Glacier and a geological wonder.