[Aim] To isolate and identify effective strains of Bacillus thuringiensis (Bt) that can kill the mosquito Culex quinquefasciatus.[Method] Soil samples were collected from several areas in Fujian Province, including Wuyi Mountain, Jianyang, Jian'ou and Pucheng. Bt strains were isolated from the soils by heat treatment and their activities against C. quinquefasciatus was determined.[Result] 71 Bt strains were isolated from 125 soil samples and subjected to bioassay. Four strains were active against C. quinquefasciatus (QQ13, QQ42, QQ66 and QQ92). Among them, QQ66 and QQ92 had the highest toxicities and harbored chitinase genes. Although cry1, cry1I, cry2, cry4, cry5, cry6, cry7, cry8, cry9, cry10 and cry11 were not detected in the two strains, they had an insecticidal crystal protein with a molecular weight of 75-100 ku.[Conclusion] The identified Bt new strains may promote the biological control of C. quinquefasciatus.