【Aim】 In order to further understand the effect of nitrogen deposition on the competitive relationship between invasive and indigenous species, and to elucidate how it changes species competitiveness and affects invasive plants. 【Method】 A de Wit replacement competitive experiment with the invasive plant Ageratum conyzoides and the native plant Acalypha australis was performed. The effects of different levels of nitrogen deposition on plant height, aboveground biomass and number of branches were simulated by watering different concentrations of NH₄Cl solutions. Relative neighbor effect (R_NE) and replacement diagrams were used to estimate interspecific competition. 【Result】 In monoculture, medium and high nitrogen treatments (6 and 12 g·m^-2·a^-1) significantly promoted the height growth and aboveground biomass of Ageratum conyzoides at harvest. whereas, the nitrogen treatment group significantly increased the height growth and aboveground biomass of Acalypha australis at harvest. When two species are mixed, regardless of the cultivation ratio, there was no significant difference in plant height between different nitrogen treatment groups during the harvest of Ageratum conyzoides. At harvest, the height of the Acalypha australis in the high nitrogen group was significantly higher than that in the control group. Medium and high nitrogen treatments significantly increased the number of branches of Ageratum conyzoides at medium and high cultivation ratios (0.50 and 0.75). Under high cultivation ratios, high nitrogen treatment significantly increased the number of branches of Acalypha australis. R_NE showed that at high cultivation ratios, the competitive effect of Acalypha australis on nitrogen treatment groups of Ageratum conyzoides was not significant. When the cultivation ratio of Acalypha australis was high, nitrogen treatment improved the competitiveness of Ageratum conyzoides, and it was most obvious under low nitrogen treatment (3 g·m^-2·a^-1). The replacement diagrams showed that the actual biomass of Acalypha australis was lower than expected under any mixed planting method. Under low nitrogen treatment, the aboveground biomass of Ageratum conyzoides and total biomass of two species were higher than expected under high cultivation ratios. 【Conclusion】 Nitrogen deposition significantly affects the growth of Ageratum conyzoides and Acalypha australis and their interspecific competition. Nitrogen deposition, especially low nitrogen deposition, increases the competitive advantage of Ageratum conyzoides.