Abstract: Understanding forest community structure is the basis for revealing community maintenance mechanism and succession dynamics, and the premise forest management activities. Taking two permanent 1-hm² plots of Quercus mongolica broadleaved mixed forest located in Wangqing Fore-st Bureau in Jilin Province as objects, we analyzed the community structure characteristics of secondary Q. mongolica forest and spatial distribution of dominant species with the point pattern analysis method (the O-ring statistics). The results showed that both plots were dominated by Q. mongo-lica with distinct hierarchy character. The co-dominated trees in plot I were Populus ussuriensis, Be-tula platyphylla, and Pinus koraiensis, which were different from plot II (Tilia amurensis, Acer mono, and Pinus koraiensis). The richness and Shannon index of plot I were higher than that of plot II. The DBH class distribution of trees in both plots were reverse-J-shaped. Individuals of Q. mongolica exhibited a normal distribution and P. koraiensis showed a reverse-J-shaped. There were differences in the diameter structure of other co-dominant tree species. The spatial distribution of Q. mongolica in two plots was aggregation distribution at small scale and random distribution in medium and large scales. P. koraiensis showed aggregation-random distribution at 0-50 m scale, while its aggregation degree in plot I were higher than that of plot II. B. platyphylla and P. ussuriensis in plot I were aggregated at the scale of 0-17 m, and the aggregation intensity was significantly higher than other tree species, and showed random distribution and uniform-random distribution at the scale of 18-50 m, respectively. Random or uniform distribution at the medium-large scale, and aggregate distribution at small scale of T. amurensis were observed in plot II. These results demonstrated that both plots were at the primary stage of succession with different growth stages. The succession stage of plot II was more progressed than that of plot I and the community of plot II was relatively more stable. Our results provide references for the precise management of Q. mongolica secondary forests at different developmental stages.