Objective To investigate the seasonal variation of malaria vectors in Nanning, China and analyze the influencing factors, and to provide a scientific support for the elimination of malaria. Methods Four villages or towns in Nanning were selected as malaria vector surveillance sites during 2015-2016. Mosquitoes caught by light traps were used to investigate the seasonal variation of malaria vectors. The collected data were analyzed using SPSS 19.0 software, and one-way ANOVA was used to compare mosquito densities. Results The total mosquito density reached its peak in May and August, whereas the density of Anopheles sinensis reached its peak in May and September. The densities of total mosquitos and An. sinensis in the cowshed were 1 242.53 mosquitoes/(light·night) and 159.12 mosquitoes/(light·night), respectively, which were significantly higher than those outdoors[49.58 mosquitoes/(light·night) and 12.30 mosquitoes/(light·night), respectively] and in the human room[15.70 mosquitoes/(light·night) and 2.91 mosquitoes/(light·night), respectively]. The densities of total mosquitos and An. sinensis in the absence of moonlight were 609.94 mosquitoes/(light·night) and 80.81 mosquitoes/(light·night), respectively, which were significantly higher than those in the presence of moonlight[212.21 mosquitoes/(light·night) and 28.92 mosquitoes/(light·night), respectively]. The density of An. sinensis was relatively high at a temperature of 25-30℃, and a humidity of 65%-75%. Conclusion The density of malaria vectors peaks between spring and summer and between summer and autumn every year. To eliminate malaria vectors, emphasis will be placed on the prevention and elimination of mosquitos in sheds. As the variation of malaria vectors differs from site to site, malaria vector surveillance should be strengthened in the local area.