With the process of urbanization, the special ground constructions and changes of atmosphere layers affect the precipitation process in the related urban regions. The urbanization process of Guangzhou is identified with the method of MODIS land cover. Based on hourly summer precipitation data in upwind of the urban, urban and downwind of the urban during 1984- 2015, the possible effects of urbanization on precipitation process were analyzed. The results show that (1) the urbanization made significant impacts on precipitation process of urban and the downwind, but had no obvious effect in upwind; (2) comparing with rainfall in the early period, the precipitation indices, including summer precipitation, precipitation days, precipitation intensity, precipitation duration etc., have obviously changed in the late period, in which urban and its downwind region experienced higher occurrences of short diachronic strong precipitation.