Podocarpus macrophyllus is a common garden ornamental and greening tree species in southern China, with high economic and medicinal value. To study the physiological response of nitrogen addition under different phosphorus environments to P. macrophyllus seedlings, two-year-old P. macrophyllus seedlings were used as the material, two soil phosphorus conditions including low additional phosphorous (0.26 g/plant), high phosphorus addition (1.08 g/plant), three nitrogen addition levels including low nitrogen addition (0.53 g/plant), medium nitrogen addition (1.06 g/plant) and high nitrogen addition (2.12 g/plant) were set up and analyzed the differences of physiological characteristics, chlorophyll content, gas exchange parameters and leaf nutrient content of P. macrophyllus seedlings in each treatment group. Nitrogen addition increased the activity of POD, and high concentration nitrogen fertilizer decreased the activity of SOD. The application of nitrogen fertilizer in a low phosphorus environment increased soluble sugars and soluble proteins, decreased MDA and Pro. Soluble protein and soluble sugar accumulation decreased in high nitrogen and phosphorus environment, but MDA and Pro increased. The chlorophyll content of P. macrophyllus seedlings was the highest under medium concentration nitrogen treatment. The addition of nitrogen in low phosphorus environment increased the P_n, T_r and G_s of P. macrophyllus seedlings, while C_i (intercellular CO₂ concentration) of P. macrophyllus seedlings decreased. The P_n, T_r and G_s were the highest and C_i was the lowest in the medium nitrogen treatment group in high phosphorus environment. P_n, T_r and G_s decreased, and the C_i increased in the high nitrogen concentration and high phosphorus environment. The same change trend of P_n and T_r and correlation analysis showed that P_n of P. macrophyllus seedlings was mainly limited by stoma factors. Nitrogen addition promoted the increase of leaf nitrogen content in low phosphorus environment, but decreased the leaf nitrogen content in high phosphorus environment. Nitrogen addition limited the accumulation of phosphorus in the leaves of P. macrophyllus seedlings, but the increase of soil phosphorus content promoted the accumulation of phosphorus content in leaves. The increase of phosphorus fertilizer concentration increased the enzyme activity of P. macrophyllus seedlings under different nitrogen treatments. The increase of nitrogen fertilizer concentration decreased the content of MDA and Pro, and the content of soluble sugar and soluble protein increased in the low nitrogen and high nitrogen treatment groups. The increase of phosphorus fertilizer concentration increased the content of MDA and Pro, and the content of soluble sugar and soluble protein decreased in the high nitrogen treatment groups. Increasing the concentration of phosphate fertilizer promoted the chlorophyll content and photosynthetic efficiency of low and medium nitrogen treatment groups, while increasing the concentration of phosphate fertilizer decreased the chlorophyll and photosynthetic efficiency.