Abstract: This paper took Xiaoxing' an Mountains of Heilongjiang Province as the research area, we analyzed the data such as the number of trees, diameter at breast height classes, tree height classes and rate of crown inclination of gap border trees in Tilia amurensis−Pinus koraiensis forest. We fitted the distribution of DBH and height classes with Weibull and normal distribution models, and then verified their fitness by Kolmogorow−Smirnov test and Chi-square test. The results showed that the number of border trees in a single gap was between 9 and 15, and most of them were formed by 9 border trees; the RCI of 67.71% of GBTs ranged from 0.5 to 0.7 while 1.04% of GBTs had regular crowns. GBTs with tree height above 25 m were widely distributed and scattered in gaps of different area. The DBH and height classes of the distribution of abundance conforms to 2 distribution models. However, the distribution of DBH, height classes and RCI of GBTs vary with the difference of gap area and tree species at the gap.