To understand the response of carbon (C),nitrogen (N) and phosphorus (P) stoichiometric characteristics of the new branches and leaves in natural Pinus tabulaeformis forest to changes in soil nitrogen concentration and differentstand age,and to reveal the response of N and P homeostasis in the new branches and leaves of Pinus tabuliformis at different stand ages to short-term nitrogen addition,taking the natural secondary forest of Pinus tabulaeformis with age V~VII of Xiaowen mountain forest farm in Guandi mountain forest area as the research object,the field in-situ comparative test with different nitrogen application rates was used to set four nitrogen application levels:control (N0,0),low nitrogen (N1,5 g/m²),medium nitrogen (N2,10 g/m²) and high nitrogen (N3,15 g/m²),and the contents of C,N and P in new branches and leaves and their stoichiometric ratios and homeostasis indexes were analyzed under different soil nitrogen concentrations.The contents of C,N and P in the branches and leaves of Pinus tabulaeformis increased significantly with the increase of soil nitrogen concentration,while the contents of C/N and C/P decreased;the contents of C,C/N and C/P in the branches and leaves of Pinus tabulaeformis increased with the increase of forest age,while the contents of N and P decreased with the increase of forest age;according to leaf N/P,the growth of Pinus tabulaeformis in this area was mainly limited by N;the relationship between N,P and N/P in new shoots and leaves with corresponding soil parameters could be adequately simulated by an internal homeostasis model (p＜0.1),the content of P in new shoots was sensitive to the change of soil nitrogen supply level,while the other indexes were stable,and the homeostasis of new leaves was higher than that of new shoots.The Pinus tabulaeformis maintained the internal stability of new branches and leaves by adjusting nitrogen and phosphorus uptake and utilization strategies to adapt to the increase of soil nitrogen concentration and the resulting changes.