The use of herbivore to manage the vegetation balance in nature reserves has great application potential. It can enhance the ecological value of herbivore, change the biodiversity of vegetation, and achieve the goal of ecological balance management in nature reserves by controlling the feeding scale. Based on the above, this paper introduced four milu (2male and 2 female) on June 5, 2021, and adopted a protective ecological grazing method to eliminate the dominant species of reed in Yeya Lake Nature Reserve. According to the implementation of the project, results show that:1) only harvesting cannot control the growth and expansion of reed. Its effect on plant diversity of phragmites australis was limited, and the structure of phragmites australis was not changed. 2) After the introduction of milu into this area, the overexpansion of cattail and reed was effectively controlled by feeding activities, swimming, lying down, and trampling; One year later, the area of cattails and bulrushes decreased by 21.96%, which provided space for the growth of scallion and hydrogonum, etc., and gradually formed a more diverse wetland environment dominated by reed and cattails. 3) The biodiversity index was further improved by increasing the landscape such as beach land and open water surface, without changing the ecological structure of surrounding floristic wetland. 4) The fauna richness of "vulnerable species" reed in Yeya Lake Wetland decreased from before 3.67 to after 1.97. The migration of milu increased the diversity of vegetation fauna, and the diversity index of reed fauna increased from 0.90 before introduction to 2.11 after introduction. In the first year of Père David's deer's introduction, the vegetation diversity index increased from 0.51 to 0.91. The migration of milu caused a significant decrease in the vegetation uniformity and degree of dominance of reed fauna in Yeya Lake Wetland, from 0.68,0.22 before introduction to 0.36,0.07 after introduction. The aboveground biomass of milu decreased from (2334.78±841.36) g/m² to (732.16±245.10) g/m². The intake of dry matter per unit area decreased from (201.87±73.11) g/m² to (57.65±18.62) g/m² after introduction. 64 species, 27 families and 56 genera of wild plants were recorded before introduction. After introduction, total of 76 species, 29 families and 64 genera of wild plants were recorded in this area, which slightly increased the number of plant species compared with that before introduction. The floristic differentiation intensity of the introduced area had no difference. The conservation value index of plant diversity was 8.25 before introduction. After the introduction of 9.06. In conclusion, one year after the introduction of milu. Under the premise of reasonable density control, the impacts were positive basically, which improved the biodiversity and wetland conservation value in the introduction area. Introduction of milu is a better scheme to enhance the diversity and improve the ecological environment of Yeya Lake Wetland. However, the monitoring period of this study is short, and the subsequent effects need to be further studied.