Objective To analyze the trend of population and density of Anopheles mosquitoes, the malaria vectors, in Jiangsu province. Methods Anopheles mosquitoes were collected by half night human baiting and overnight light trapping from July to September in 2015 in south, north and part of middle Jiangsu counties and districts. The biting rates and the density of light trapping were analyzed. Results A total of 1 942 Anopheles mosquitoes were collected on 11 surveillance sites from July to September in 2015 by half night human baiting. All collected Anopheles mosquitoes were identified as An. sinensis. The biting rates of An. sinensis for the first ten days and last ten days each month during July to September were 3.93, 4.79, 3.22, 2.31, 1.23, and 0.71 mosquitoes/person·hour, among which the rates during 19:00 to 24:00 were 2.73, 3.15, 2.81, 2.65, and 2.16 mosquitoes/person·hour. Using overnight light trapping, 3 602 Anopheles mosquitoes were collected and identified as An. sinensis. The indoor density of An. sinensis for the first ten days and last ten days each month during July to September were 5.61, 7.45, 8.10, 3.88, 1.85, and 0.94 mosquitoes/night·light, while the outdoor density were 16.30, 18.10, 25.03, 15.94, 5.76, and 4.09 mosquitoes/night·light. Conclusion The malaria vector in Jiangsu province is An. sinenesis. The peak of activity for An. sinensis is from late July to early August. The activity frequency of An. sinensis is higher in the first half night, especially during 20:00-21:00. Anopheles sinensis stays outdoor longer than indoor. To reduce the mosquito-borne diseases among residents, the health education on mosquito prevention is needed to be strengthened.