Soil nitrogen and moisture content are important factors that limit plant growth in forest ecosystems. In order to investigate the response of evergreen broadleaf tree species to increased nitrogen deposition and decreased precipitation, we conducted a common garden experiment in Fenyi county, Jiangxi Province. Five-year-old saplings of Castanopsis fargesii, Cyclobalanopsis jensenniana, and Quercus acutissima were subjected to control, nitrogen application (+N, 60 kg hm^-2 a^-1 nitrogen addition), rainfall exclusion (-W, natural rainfall reduced by 50%), and their interaction (+N-W, 60 kg hm^-2 a^-1 nitrogen addition together with natural rainfall reduced by 50%) respectively, and their total biomass, biomass of organs, and biomass allocation were analysed. The results showed that:(1) Nitrogen application increased the total biomass, the biomass of organs, and biomass allocation of the saplings of three species significantly compared to the control (P < 0.05). (2) Rainfall exclusion reduced the total biomass, the biomass of organs and biomass allocation non-significantly (P > 0.05). (3) Except for leaf and branch biomass of Q. acutissima, the interaction of nitrogen application and rainfall exclusion had no obvious effect on the total biomass, the biomass of organs, or biomass allocation of the the saplings of three species compared with the control (P > 0.05). (4) Nitrogen application increased the trunk weight ratio of C. fargesii, trunk weight ratio and branch weight ratio of C. jensenniana(P < 0.05), reduced the leaf weight ratio and root weight ratio of C. jensenniana (P < 0.05). (5) Rainfall exclusion increased the root weight ratio of C. fargesii and Q. acutissima, root-shoot ratio of Q. acutissima(P < 0.05), reduced the branch weight ratio of C. fargesii, leaf weight ratio, branch weight ratio and trunk weight ratio of Quercus acutissima(P < 0.05).(6)The interaction of nitrogen application and rainfall exclusion increased the root weight ratio of C. fargesii (P < 0.05), reduced the trunk weight ratio of Quercus acutissima(P < 0.05).