Objective To investigate the densities of Culex tritaeniorhynchus in surrounding areas of Beijing Capital International Airport during 2011 to 2013, and to provide a scientific basis for the control and prevention of Japanese encephalitis (JE). Methods Seven monitoring stations within 2000 meters around Beijing Capital International Airport were included in this study. Carbon dioxide light traps were used to capture mosquitoes according to GB/T 23797-2009. Descriptive epidemiological analysis was performed with mosquito density monitoring data from 2011 to 2013 in surrounding areas of Beijing Capital International Airport. Analysis of variance was used in comparison of mosquito density. The correlation analysis between incidence of JE and density of Cx. tritaeniorhynchuswas carried out by Pearson correlation coefficient.Results A total of 88 789 adult mosquitoes were captured within the 3 years of investigation.Cx. pipiens pallenswas the predominant mosquito species (accounting for 80.54% of all captured mosquitoes), followed by Cx. tritaeniorhynchus(18.89% ). The annual average density indices ofCx. tritaeniorhynchusin the 3 years were 4.31, 1.62, and 13.01 mosquitoes per light-hour, respectively, without significant differences between them (F＝1.579,P＞0.05). AdultCx. tritaeniorhynchuswas only captured between August and October during the 3 years. The monthly average densities were 1.04, 32.00, and 1.15 mosquitoesper light-hour, respectively,with significant differences between them (F＝5.831, P＜0.01). The density of Cx. tritaeniorhynchusin September was significantly higher than those in August and in October, and the highest density appeared at mid-September. Adult Cx. tritaeniorhynchuswas captured in all seven monitoring stations, with densities ranging from 0.44 to 41.09 mosquitoes per light-per hour.Cx. tritaeniorhynchusdensity was the lowest in residential area and the highest around the Wenyu river system. No significant difference was found between seven monitoring stations (F＝1.368,P＞0.05). In the 3 years, only 3 JE cases were reported from September to October in 2013, from Shunyi district, where Beijing Capital International Airport was located. Apositive correlation was found between the incidence of JE and the density ofCx. tritaeniorhynchus(rs＝0.898,P＝0.015).Conclusion The density and constituent ratio ofCx. tritaeniorhynchuswere high in surrounding areas of Beijing Capital International Airport. Cx. tritaeniorhynchusmainly inhabited outdoor environments such as riverside. The activity peakof Cx. tritaeniorhynchuswas between August and September, which coincided with the epidemic period of JE. The density of Cx. tritaeniorhynchuswas positively correlated with the incidence of JE. Therefore, surveillance ofCx. tritaeniorhynchusshould be strengthened.