Abstract: The Cupressus chengiana S.Y.Hu is one of national second-level protected species,mainly distributed in the basins of Minjiang,Dadu and Bailong rivers.Its natural distribution area is also the living area of residents,and therefore being affected by grazing,cutting,wood burning and other human activity disturbance.Based on the disturbance type and intensity,the C.chengiana forests were divided into excessive,severe,moderate and mild disturbance types,respectively.In order to answer the affects of different disturbance intensity on the C.chengiana population characteristics,analysis was made of population density,heights,DBH and population structure of different disturbance types.The results showed that trees of C.chenginia of all levels of DBH,heights and basal diameter scattered under mild disturbance type,but the percentage of seedlings and saplings was small,intermediate grade trees were more,hence the population structure was reasonable.Under moderate disturbance,small levels of C.chengiana accounted for the main body,middle level trees had also some distribution,and C.chengiana populations might returns to the normal state.Under the severe disturbance,there were many low level trees,but the higher level trees were scarce.Under the excessive disturbance,there were not higher level trees.In a word,the tree age,height,DBH,and DBH structure were more reasonable,and the population could naturally regenerate under the mild and moderate disturbance.But the rationality and stability of population structure was bad,and could hardly complete natural regeneration under the excessive and severe disturbance.