Abstract: By taking Picea purpurea population as a group of trees in various classes of D.B.H.,its quantitative dynamics is described with Leslie matrix.The eigenvalue of this matrix for Picea purpurea is 1.028 or λ=1.028,and the eigenvector which reprents its stable structure is(9941,783,556,393,280,116,32,8).The result demonstrates that the population structure of Picea purpurea is stable and shows its growing stability.The future structure of the population will be similar to the present one according to the prediction.