Abstract: Objective To understand the structure characters of Pinussylvestris var. mongolica natural forest on Honghuaerji sandy land and provide the basis for protection and management. Method The data of 2 sample plots of 100 m×100 m with each tree positioning were analyzed by the characteristics of univariate distribution and bivariate distribution with statistical software. Result The results show that (1)The diameter at breast height (DBH) distribution of P.sylvestris var. mongolica natural forest follows a single or multi shaped peak curve, and the vertical structure is simple, with only tree layer and herb layer. (2) The spatial distribution pattern of P.sylvestris var. mongolica natural forest is uniform distribution, close to random distribution; the spatial distribution pattern has nothing to do with the stand density; the stand in the fierce competition in the majority of individuals of P.sylvestris var. mongolica. (3) Under the condition of random distribution, most trees on the two sample plots are medium dense or dense, with little difference in dominance under different distribution patterns. In low-density P.sylvestris var. mongolicapure forest, most trees in intensive state aredominant trees, while in high-density forest, no relation was found between stand density and tree size distribution. Conclusion The structure of P.sylvestris var. mongolica natural forest on Honghuaerji sandy land is unreasonable; some measures of density adjustment and structure optimization should be taken to improve the forest health.