Diameter frequency distribution in a specific stand provides basic information for forest resources management.In this study,four probability models were applied to analyze diameter distribution of natural forests after selective cutting with different intensities (low intensity of 13.0% in volume,medium intensity of 29.1%,high intensity of 45.8%,and extra-high intensity of 67.1%).The results show that the skewness and kurtosis of the four models are positive except that of low intensity selective cutting,which suggest that the number of small-size trees dominate the stand.The more intensity of selective cutting,the wider range of diameter distributions.The diameter structure of selective cutting with low intensity met Weibull and Beta distributions;that of medium intensity met Weibull,negative exponential as well as Gamma distributions;that of high intensity cutting met Weibull and negative exponential distributions,but that of extra-high intensity could not meet any above model.Weibull distribution model fits better than others regarding the structure of diameter distribution in natural forests managed on polycyclic cutting system.The results will provide basic information for sustainable management for mixed natural stands managed on a polycyclic cutting system. In this study, four probability models were applied to analyze diameter distribution of natural forests after selective cutting with different intensities (low intensity of 13.0% in volume, medium intensity of 29.1 %, high intensity of 45.8%, and extra-high intensity of 67.1%). The results show that the skewness and kurtosis of the four models are positive except that of low intensity selective cutting, which suggest that the number of small-size trees dominate the stand.The more intensity of selective cutting, the wider range of diameter distributions.The diameter structure of selective cutting with low intensity met weibull and beta distributions; that of medium intensity met weibull, negative exponential as well as Gamma distributions; that of high intensity cutting met Weibull and negative exponential distributions, but that of extra-high intensity could not meet any of the above models. Weibu ll distribution model fits better than others regarding the structure of diameter distribution in natural forests managed on polycyclic cutting system. the results will provide basic information for sustainable management for mixed natural stands managed on a polycyclic cutting system.