Abstract: The composition of groups,the structure and seasonal variation of soil fauna in Chongqing Airport grassland in 1995-1996 were investigated.The relation between soil fauna and birds was preliminarily analyzed.The results showed that Aacarina was the dominant group,and the common-seen groups were soil macrofauna and mesofauna,which were birds main prey.Soil microfauna whose activity was weak,and its likely to live in soil and humus.Soil macrofauna whose activity was strong,its likely to live on ground and moved as the environment changed.The measure of soil microfauna diversity and stability were better than those of soil macrofauna.Both the groups,the individuals and the community diversity of soil fauna in autumn and winter were more than those in spring and summer.This provided food resources for the birds in Chongqing Airport grassland.Thus effect that soil fauna variation has an influence on the birds action.Comparing the seasonal variation of species and individuals of soil fauna,we found a hysteretic phenomenon on time to the seasonal variation of species and number of individuals of birds.