Based on the vegetation community survey of a 1 hectare plot in Forest Farm of Mulanweichang

and by using the mingling degree

neighborhood comparison and uniform angle index

the spatial structure characteristics of nature secondary forest in rocky mountain area of Northern China were analyzed.The results showed that Betula platyphlla was the dominant and constructive species of the tree layer

its mingling degree was low

but the mingling degrees of sub-dominant and associated trees were big.The mainly mixed forms of the stand were none-mixed or less-mixed

the average mingling degree was 0.400.The order of tree species neighborhood comparison was as follow: Larix principis-rupprechtii

Sorbus pohuashanensis

Quercus mongolica

Betula dahurica

B.platyphlla

Picea wilsonii

Populus davidiana

Pinus tabulaeformis and Acer truncatum.In the vegetation community

most of the trees were in the random distribution

but the average uniform angle index of the stand was 0.562

so the distribution pattern of the overall stand was aggregative distribution.According to the spatial structure characteristics of nature secondary forest

the tendency of community succession and some management advices were proposed.