Abstract: Atmospheric nitrogen (N) deposition dramatically raised in recent decades, resulting in increases of soil N availability and N/P ratio, which would impact plant growth and P efficiency under low P stress. Taking breeding population of Pinus massoniana as test materials, a pot experiment was conducted to simulate two P conditions, i.e., homogeneous low P availability vs. heterogeneous low P among soil layers, in combination with two N deposition levels on growth traits and P absorption and utilization efficiency of P. massoniana. Under the homogeneous low phosphorus condition, growth traits and P efficiency of P. massoniana were not significantly improved by simulated nitrogen deposition, but significant nitrogen × family interaction effect was detected, with the biomass of family 40×44 and 71×20 being increased, 36×29 and 73×23 being decreased. Under the heterogeneous low P condition, significant N effects on the seedling height, biomass and P absorption efficiency were observed, due to promoted root length and root distribution ratio of topsoil. In addition, the effects of simulated N deposition on growth and P efficiency of P. massoniana were relevant to the N/P ratio. Under the homogeneous low P condition, the N/P ratio of P. massoniana plant was 13.8, plants exhibited a low sensitivity to simulated N deposition, root secreted APase activity was increased but the plant growth was not promoted. In comparison, the plant N/P ratio was 9.7 under the heterogeneous low P condition, and the plant growth and P efficiency were significantly promoted, while no obvious change occurred in root secreted APase activity.