Abstract: In order to analyse the transmission dynamics of bancroftian filariasis, an investigation of some entomological parameters was carried out in Queshan County, Henan Province. The results were as follows:1.From July to September during 1982-1984 the average of man-biting rate of Culex pipiens pallens in residents sleeping outdoors and in those using mosquito nets were 108 and 45/per person per night, respectively (Table 1).2.A total of 1851 Culex pipiens pallens were dissected, the parous rate was 0.386.3.The duration for the mosquito from blood-taking to oviposition was 4.5 days on average and the first gonotrophic cycle was around 5.5 days.4.The daily survival rate of the mosquito calculated was 84.1%.5.Eleven days were needed for the development from microfilaria to infective larva in mosquito.6.The proportion of infective mosquito calculated by the daily survival rate and the days needed for development of mature filaria larvae in mosquito was 0.149 which, was very close to 0.153 obtained in the field observation.7.The human blood index of Culex pipiens pallens was 0.81.