Abstract: Under laboratory condition, the larvae of Culex pipiens Fatigans may feed a lot on Anabaena sp. and complete their life cycle. The retention time of Anabaena sp. in larval intestine was about 6 hours, while that of saccharomyces was about 5 hours, meaning that Anabaena sp is not so digestible for the larvae. From hatching to pupation, the larvae fed with Anabaena sp. lasted 194 hours and those fed with Saccharomyces were 142 hours, showing that the duration for complete larval stage of the former is 52 hours longer than that of the latter. By test, the optimum feeding conditions for mosquito larvae on Anabaena sp. are 7-8 in pHand 25-30℃ in water temperature. An increase in feeding quantity was observed when Anabaena sp. increases in density or mosquito larvae increased in size.