Objective To analyze the association between the seasonal fluctuation of mosquito density and mosquito-borne diseases in Hebei province. Methods We collected the incidence data of the mosquito-borne diseases and the monitoring data about seasonality of mosquito population density in Hebei province during the period of 2013-2015, and then all the data were analyzed by using SPSS 21.0 software. Results The total of mosquito-borne diseases in Hebei province during the period of 2013-2015 were 467 cases. The main mosquito-borne diseases were epidemic encephalitis, malaria and dengue fever. The number of cases are 264, 178 and 25 cases respectively. In total, 71 916 mosquitoes were captured during the period of 2013-2015 in Hebei province and the monthly average mosquito density was 1.368 per mosquito-lured lamp. Culex pipiens pallens(1 515), Cx. tritaeniorhynchus(208), Aedes albopictus(150)and Anopheles sinensis(10)were common in Hebei province, the population density of Cx. pipiens pallens was the highest, accounted for 97.38% of the total mosquitoes. The incidence of mosquito-borne diseases was correlated with mosquito population densities during 2013-2015 (r=0.145, P=0.041). Conclusion The results suggest that there are many kinds of mosquitoes in Hebei province and there are complex links between mosquito population densities and mosquito-borne diseases.