Objective To understand the variation of mosquito species,density and seasonal fluctuation in Shenyang,and to provide scientific basis for mosquito control.Methods From May to October 2020 to 2023,mosquito traps were used to monitor mosquitoes in urban areas(residential areas,parks and hospitals)and rural areas(farmers and livestock sheds)in Shenyang.Results A total of 19 734 mosquitoes were captured in Shenyang from 2020 to 2023,and the top 3 mosquito populations were Aedes vexans,Culex pipiens pallens and Anopheles sinensis,accounting for 54.25%,25.51%and 18.15%,respectively.The average mosquito density in 2020,2021 and 2023 was 39.47 mosquitoes/(light·night),the highest density was 414.29 mosquitoes/(light·night)in livestock sheds,and the lowest density was 2.75 mosquitoes/(light·night)in hospitals.The seasonal fluctuation of mosquitoes showed a unimodal curve,and the peak of mosquito density in each year was from July to September.Conclusion Livestock sheds and farmers are the key places for mosquito control in Shenyang,and more attention should be paid to the places where Anopheles sinensis and Aedes koreanus were detected to effectively control mosquito-borne infectious diseases.