Abstract: Abstract: 【Objective】The aim of this study was to investigate the effects of thinning intensity on soil nitrogen content and the soil nitrogen-cycle enzyme activities in the rhizosphere soil of Pinus massoniana plantations, which could provide reference data for the sustainable management of P. massoniana plantations.【Method】Soil samples were collected from the rhizosphere of P. massoniana plantations, which were thinned at different intensities(control(CK), 0%; light intensity thinning(LIT), 25%; moderate intensity thinning(MIT), 45%; and heavy intensity thinning(HIT), 65%), to study the effect of thinning on soil nitrogen, and to assess the associations among soil nitrogen, enzyme activities, and physicochemical properties.【Result】 Compared to that in CK, ammonium nitrogen content of rhizosphere soil was significantly increased in LIT, but was decreased in HIT. The total nitrogen, nitrate nitrogen, and dissolved organic nitrogen contents of rhizosphere soil were in the order of MIT>CK>LIT>HIT. Both microbial biomass nitrogen and alkali-hydrolyzable nitrogen contents of rhizosphere soil increased in LIT and MIT. LIT and MIT significantly decreased urease activity of rhizosphere soil, but increased the nitrite reductase activity. The effects of thinning on soil protease, nitrate reductase, and hydroxylamine reductase activities were not significant, indicating that urease and nitrite reductase are more sensitive to thinning, and may serve as indicators of soil nitrogen dynamics. In addition to nitrate reductase activity, the other four nitrogen-cycle enzyme activities and the nitrogen content of rhizosphere soil were higher than those of the bulk soil, indicating a positive rhizosphere effect. Moreover, soil nitrogen content and enzyme activities were closely correlated with the soil water content and pH.【Conclusion】Thinning had significant effects on soil nitrogen content by changing soil water content and enzyme activities. We recommend LIT and MIT as efficient management practices for improving the efficiency of soil nitrogen use in P. massoniana plantations.