The timberline ecotone is important in climate change study as an early-warning region. The survival and development of planted forests at the tree line has significant effects on landscape ecosystems in natural reserves. Larix principis-rupprechtii,which has definite dominance on treeline of Wutai Mountain,was selected as the research target. A 50m*50m sampling plot was set up,and information about the species in the community were collected in 5 random quadrats ( 10m*10m) within the sampling plot,diameter at breast height ( DBH) and location of trees were measured and recorded. Point pattern analysis and null models of Complete Spatial Randomness ( CSR),Heterogenous Poisson ( HP), and Random Labeling ( RL) were adopted to analyze the pattern and process of the dead and surviving individuals of Larix principis-rupprechtii on 025m scales. The results of analysis were the following: According to DBH statistics,the average DBH of surviving trees was 11.54cm,and that of the dead trees was 8.27cm. As for the tree growth rate,the DBH of Larix principis-rupprechtii was smaller than that in other areas,and the slow growth was a result of adaptation to the timberline ecotone. Dead tree had larger clusters and aggregation at 015m scales,and surviving trees aggregated at the <3m and 21m scales. The difference between the Heterogenous Poisson ( HP ) simulation pattern and the observed pattern for surviving trees was not significant,which meant that spatial heterogeneity explained the pattern of tree survival well. The Random Labeling ( RL) simulation result showed that surviving trees had negative correlations with dead ones around 21m, and that mortality was caused by negative density dependence,especially for sapling trees. Meanwhile,results speculated that inter-specific interactions between shrubs and sapling trees had effects on tree death.