Abstract: Analysis on the protein / polypeptide in Culex pipiens pallens ( Diptera : Culicidae) caught from the resting or overwintering places during the 3rd ten-day of September,the 2nd ten-day of December and the 1st ten-day of March in next year in Zhengzhou(34°43'N ,113° 39' E) during hibernation by two-dimensional gel electrophoresis indicated that there were 153, 118 and 169 protein/polypeptide spots in unoverwintering, overwintering and recovering mosquitoes respectively. The molecular weight (MW) of most of the spots was less than 43. 0 kDa, with isoelectric points (pI)between 5. 65-7. 34. The comparisons between each two types of mosquitoes during hibernation revealed that the variant rate of protein / polypeptide spots between overwintering and recovering mosquitoes (31. 01 % ) was significantly higher than that between unoverwintering and recovering females (21.12%) (P0. 05). The variant spots were 13 in unoverwintering, 7 in overwintering and 27 in recovering mosquitoes respectively. The comparisons among three types of mosquitoes during hibernation showed that the variant rate was significantly higher in recovering females(15. 98%) than in unoverwintering (8. 50%)(P0. 05)and overwintering females(5. 93%)(P0. 01). The total variant rate of protein/polypeptide spots of all these three types of mosquitoes was 10. 68%.Because the blood meal of all the mosquitoes used for homogenization was at Sella 1 (empty), and the ovary development was under Christophers Ⅱ(resting stage), the experimental results were not affected by blood meal and the later ovary development (Christophers Ⅱ-Ⅴ).