Objective To investigate the species and spatial distribution of adult mosquitoes, distribution of the breeding sites, and water pH value, which would provide a scientific basis for predicting the spread of mosquito-borne diseases, developing the prevention and control strategy and construction of hygienic town. Methods The adult mosquitoes and larvae were captured using mosquito lure lamp method and scoop method respectively. The longitude, latitude and altitude of the collection sites, and the pH value of the water for larvae breeding were recorded. The species and composition of mosquitoes caught in Minhe county of Qinghai province in June 2017 were statistically analyzed. Results A total of 169 adult mosquitoes were captured, including 141 female and 28 male mosquitoes, with the density of 13 insects/(lamp·hour), belonging to 6 species, 4 genera. The predominant species were Culex pipiens pallens, Aedes vexans, and Anopheles sinensis. The altitude of breeding sites ranged from 1 759 m to 2 207 m, and pH of water was between 7.1 and 9.0 for mosquito larval breeding sites. Conclusion The mosquito species found in Minhe county was in accordance with the records of Qinghai provincial epidemic prevention station. And it was the first time to report that the water is appropriate for larval breeding when the pH value is 9. Anopheles sinensis, the important vector of malaria, was found in the dense residential areas of Minhe county, which indicated that there was the transmission risk of malaria. We should strengthen monitoring, improve the prevention and control measures, and implement risk assessment of the mosquito-borne diseases, such as Dengue fever.