Abstract: Objective To understand the population density and seasonal fluctuation of Culex tritaeniorhynchus in China and provide evidence for the control and surveillance of Culex tritaeniorhynchus and related communicable diseases. Methods Light traps were used in the density surveillance for Culex tritaeniorhychus in residential areas, parks, hospitals, farmyards and livestock sheds in China from 2006 to 2012. Results From 2006 to 2012, the overall average density of Culex tritaeniorhynchus was 0.82 mosquito/trap/hour. The densities of Culex tritaeniorhynchus in Jiangsu (in eastern China), Hunan and Hubei provinces (in central China) were higher than those in other provinces. The region and season specific differences in the density were statistical significant. The density was highest during May-June in southern China, during June-August in southwestern China, during July-August in eastern, central, northern and northwestern China and during August-September in northeastern China. The densities in farmyards and livestock sheds were higher and the differences in the density in 5 environments had statistical significance. One annual density peak was observed, which was in July in livestock sheds and during June-August in farmyards. The annual density was different, which was highest in 2010 and lowest in 2012. Conclusion The information about the overall density of Culex tritaeniorhynchus and its regional, habitat, annual and seasonal differences in China were obtained, which provide evidence for the surveillance, risk assessment of Culex tritaeniorhynchus and early-warning, and control of related communicable diseases.