Abstract: Urbanization is an inevitable law of economic and social development, but rapid urbanization may bring about many negative effects, one of the possible negative effects is the decline in social trust. Urbanization will break the original social network, trigger the resource competition, increase the uncertainty of the external environment, and cause the exclusion of new immigrants by the original residents. All of these may aggravate social conflicts and worsen social trust. The findings of the research based on the data from the Chinese General Social Survey (CGSS) show that the level of social trust decreases significantly with the increase in the speed of urbanization, especially, rapid urbanization will significantly reduce the level of social trust. In view of the fact that the decline in social trust will lead to many major negative effects, it is very necessary for the government departments to pay attention to this issue in the process of rapid urbanization.

Key words: urbanization, social trust, social network, uncertainty