[Objective] The objective of this study is to analyze the influences of N addition on population characteristics and reproduction strategies of Bothriochloa ischaemum population in order to assess the impact of N deposition on the ecological environment. [Methods] This study was conducted to investigate the responses of population characteristics and reproduction strategies of B. ischaemum population to N addition based on four N addition treatments, including control CK(0 g/(m²·a)), low nitrogen (2.5 g/(m²·a)), middle nitrogen (5.0 g/(m²·a)) and high nitrogen (10.0 g/(m²·a)) for two years. [Results] (1) The N addition significantly increased the height and biomass of B. ischaemum population, population biomass reached the maximum with middle nitrogen treatment. (2) N addition had changed the nutrient allocation strategies of B. ischaemum. Root-shoot ratio decreased with the increments of N addition. (3) N addition promoted sexual reproduction and vegetative propagation of B. ischaemum population, enabled its high ability of breeding and competition. [Conclusion] Moderate N sedimentation or N addition (<5 g/(m²·a)) can promote the growth and development of B. ischaemum population, and improve its ecological function in soil and water conservation.