On the basis of the data from four investigations between 1987 to 2003 of overcut spruce-fir forest in Jingouling Forest Farm,Wangqing Forest Bureau,Jilin province.The author analyses the number distribution characteristic at different diameter grades,and describes the diameter structure with two kinds of functions of Weibull distribution and negative index distribution.The results show that the diameter distributions are complied to the uneven-aged stand.Both Weibull distribution and negative index distribution can be used to describe the stand diameter structure of overcut spruce-fir forest and the former is better than the latter.