Aims Due to human activities, nitrogen (N) deposition is increasingly serious, and phosphorous (P) fertility is widely applied in the soils of subtropical forests suffering from P deficiency, but there are relatively few researches of N and P additions on soil characteristics of subtropical forests. Difference in stand density may affect light, temperature, water and litter water holding capacity, which may influence soil characteristics. The effects of external nitrogen and phosphorus and stand density on soil chemical property were investigated in 10 years-old Acacia auriculiformis stands in order to provide a scientific basis for stand density and forest soil management.Methods In this study, five subsample plots were established in the stands with four densities (1 667, 2 500, 4 444 and 10 000 trees·hm -2) and treated with N addition, P addition, N+P addition and control from 2013 to 2015. At the end of experiment, soils at 0-10 cm depth with different treatments were collected and pH value, organic matter content, N, P and K contents were analyzed in the A. auriculiformis stands.Important findings The results indicated that soil pH value and available potassium (K) content significantly decreased, whereas soil alkalized N content significantly increased after N and N+P additions in the four density stands, and soil total N content significantly increased after N addition. Soil pH value significantly increased and soil total N content significantly decreased after P addition. Contents of soil organic matter, total P and available P significantly increased after P and N+P additions. With the increase of stand density, the contents of soil organic matter, total N, alkaline N, total P, available P and available K significantly increased. The interactive effects of density and N and P additions on soil pH value, organic matter, N, P and K contents were significant in the stands. Generally, the effects of N and P additions, stand density and the both interaction on soil chemistry property were significant.