Abstract: The objective of this study was to explore the characteristics of diameter at breast height(DBH) classes and tree height classes of 358 gap border trees (GBTs), and analyze the relationships among DBH class,tree height class, distribution of rate of crown inclination (RCI) and forest gap size.The gap border trees were selected from 32 gaps. We fit the distributions of DBH and tree height classes with Weibull and normal distribution models, and then verified their fitness by Kolmogorov and Chi-square tests. The results showed that the distribution of DBH classes of GBTs followed Weibull distribution rather than normal distribution,but the distribution of tree height classes complied with bothWeibull and normal distributions. The RCI of 65.36% of GBTs ranged from 0.5 to 0.7 while 15.08% of GBTs had regular crowns. There was a highly significant difference in RCIs between different tree species. No significantly linear correlation could be found between mean RCI in a single gap and its size of area. The proportion of gap with 10 GBTs was the highest,reaching 21.88%,and each gap had averagely 11.19 GBTs.