Abstract: An investigation was conducted in a 2.55 hm² plot of Pinus koraiensisdominated broadleaved mixed forest to study the microsite characteristics of pit and mound formed by 42 treefalls and the status of vegetation regeneration on the microsites. The soil water content, soil temperature, relative air humidity, and photosynthetically active radiation (PAR) on five microsites (mound top, mound face, pit wall, pit bottom, and intact forest floor) were measured. Among the five mirosites, mound top had the highest PAR (527.9 μmol·m^-2·s^-1) while intact forest floor had the lowest one (58.7 μmol·m^-2·s^-1), mound top had the highest soil temperature (16.0 ℃) but pit bottom had the lowest one (13.3 ℃), pit bottom had the highest soil water content (34.6%) but mound face had the lowest one (0.5%), and intact forest floor had the highest relative air humidity (75.9%) but mound top had the lowest one (68.0%). The frequency of forming pit/mound complex by the tree species was decreased in the order of Pinus koraiensis (42.9%)>Picea asperata (31.0%) > Betula platyphylla (16.7%) > Abies fabri (7.1%) > Prunus padus (2.4%). Among the 42 treefalls, twothirds of them were in northwest direction. The treefalls volume had significant positive correlations with pit depth, pit length, mound height, and mound width, but negative correlation with mound thickness. The treefall mean diameter at breast height had significant positive correlations with pit width (r=0.328, P=0.017) and pit length (r=0.527, P=0). The tree species richness at the microsites decreased in the order of intact forest floor > pit > mound, and the tree species coverage was in the sequence of intact forest floor > pit > mound.