Abstract: In this paper, the TWINSPAN classification method was used to quantitatively classify mixed forest in Jingouling forest farm. Then the classification results was used to analyze succession law of mixed forest. The mixed forest of the farm was divided into seven types with characteristics of area proportion increased gradually. The proportion of mixed conifer and broadleaf forest of Picea sp., Abies sp., P. koraiensis, Tilia sp., B. costata and Acer sp. was the highest, the second was mixed conifer and broadleaf forest of Picea sp., Abies sp., P. koraiensis, B. platyphylla, Populus sp., B. costata and Tilia sp.. The proportion of these two types was 554％ of total. It showed that mixed conifer and broadleaf forest of Picea sp., Abies sp., and P. koraiensis was main forest type in the farm. The proportion of mixed forest of broadleaf and P. koraiensis, the climax community of this region was only 84％. Succession law analysis indicated that succession characteristics of seven types were distinctive. The total trends were that pioneer tree species changed from puniness to mightiness, associated tree species and climax conifer tree species changed from mightiness to puniness. It well formed mixed forest of broadleaved tree and Korean pine with steady tree species structure finally. The results showed that using TWINSPAN method to classify and sort mixed forest was feasible.