AIM: To observe the dynamic changes of Anopheles sinensis under natural condition. METHODS: By means of the life table, the 5th, 6th, 7th and 8th generation of the Anopheles sinensis natural population in Zhengzhou reion was studied from 1994 to 1995. RESULTS: According to the life tables established we can see that during rainy seasons, K₅ was the highest among all of the K- values, followed by K₉. Key factor analysis was conducted by using Varley’s diagram and Podoler’s regression method, respectively. The survival curves of 5- 8 generations were plotted in terms of the life table data in 1995. The population tendency indices (I) of all life tables were greater than 1 and the I- value of the 5th generation was the highest. CONCLU-SION: The first key factor of the natural population of An. sinensis was the death of the 1- 2 instar larvae caused by the heavy storm and the second was the predatory death of the 3- 4 instar larvae. The highest mortality occurred at the stage of 1- 2 instar larvae. The type of survival curves belonged to Slobodkin IV. The results showed that the number of the natural population of An. sinensis in Zhengzhou region increased during the June, July and August, the increase in the number of the 5th generation (I =34.4584) being the highest.