Abstract:The Gongga Mountain is located on the southeast edge of the Qinghai- Xizang (Tibet) Plateau and is in the middle of the Great Snowy Mountain Range of the Hengduan Mountain System, with its main peak being 7 556m above the sea level. Picea brachytyla mainly distributes on the east slope and its distributional range of altitude is between 2 300m to 2 800m.We used five methods to study the spatial pattern of different communities dominant by Picea (brachytyla. The results show that most of the species were of clumped distribution type. However, the edificator, Picea brachytyla, was of the random distribution type. Our studies on the spatial pattern of trees in different sublayers and the Morisita Index using plots of varying sizes have revealed that the spatial pattern changes as the community develops, and is influenced by the formation of microhabitats, such as tree gaps. The factors responsible for the dynamic changes of the spatial pattern with forest age include self-thinning and alien-thinning caused by intra- and interspecific competitions in the community.The association coefficients and a 2× 2 contingency table were used for the measurement of interspecific association. Based on the semi-matrix diagram of 62 tree species, we divided them into four closely linked natural groupsm of which two groups are very clear,one is suitable for higher altitude, and one has been invaded by broadleaf trees.The combination of spatial pattern analysis with interspecific association measurement may be one of the approaches to explain the distributional range of species, population structure, community succession, as well as the diference in their habitats.