Abstract: For effectively using natural enemies to control tobacco pests, the life cycle and population dynamics of Chrysopa pallens (Rambur) in tobacco field were investigated. The results showed that the insect produced 5-6 generations in tobacco growing area in Mile,Honghe Prefecture,Yunnan. Its egg changes color along with the embryonic development,and the duration of egg color changing was the shortest in the 4th generation. From late June to early July was the first peak of adult occurrence in tobacco fields,from late August to early September appeared another peak. The population dynamics of Chrysopa pallens (Rambur) in tobacco field presented a double-peak profile.