Abstract:This paper is based on the 12 year-old Cunninghamia lanceolata at Dagang mountain in Jiangxi provience, 41 piots and 41 average trees were studied. It dealed with ecological characteristics of Cunninghamia lanceolata plantation, the regulation of density effect in different site conditions, biomass as well as productiviety afforestation. According to the method of b value analysis, the results show that the primary and management density in low index of position area must be more than high index of position area, the difference is 600 tree/ha.