Abstract: Larix principis-rupprechtii and Picea wilsonii were dominant tree species of cold temperate coniferous forest in Pangquangou National Nature Reserve. In this paper,population structure and distribution types of mixed forest and single forest were studied.Analysis of size structure showed in mixed forest,Larix principis-rupprechtii populations were declined,Picea wilsonii populations were increased.Because of sufficient saplings of Picea wilsonii and few saplings of Larix principis-rupprechtii,the mixed forest would change into Picea wilsonii forest in certain time.Single forest of Larix principis-rupprechtii and Picea wilsonii were both increased for sufficient saplings,so they would retain current structures in long periods.The whole population distributions of cold temperate coniferous forest were clumping distributions.The clumping degree in mixed forest was stronger than in single forest,which greatly because of different demands of sunlight between the two populations.The clumping degree of old temperate coniferous forest was decreased as size class increased.Of Larix principis-rupprechtii populations,saplings were greatly clumped under gaps,clumping degree dropped down in adults.Of Picea wilsonii populations,saplings were greatly clumped in both single and mixed forests;while adults were clumped in single forests and random distri-buted in mixed forests.