Background Secondary forests have become the major forest type worldwide. Research on spatial patterns and associations of tree species at different developmental stages may be informative in understanding the structure and dynamic processes of secondary forests. Methods In this study, we used point pattern analysis to analyze the spatial patterns and associations of tree species at seedling, sapling and adult stages in a 4ha plot in the montane secondary temperate forest of northeastern China. Results We found that species showed similar patterns at seedling, sapling and adult stages, and aggregation was the dominant pattern. The spatial patterns of tree species were mainly affected by habitat heterogeneity. In addition, the strength of positive or negative associated pattern among tree species would decrease with developmental stages, which attributed to neighborhood competition and plant size increasing. Conclusions Our results indicated that the spatial patterns and associations of tree species at seedling and sapling stages partly reflected that at adult stage; habitat heterogeneity and neighborhood competition jointly contributed to species coexistence in this secondary forest.