The ecological effect of nitrogen fertilizer with split application on rice rhizosphere microbes was conducted in paddy field of Fuyang, Zhejiang province, China in 2005. The research rest, lts indicated that the ecological effect of nitrogen on rice rhizosphere microbes is not only affected by rice rhizosphere microbes population but also affected by the growth of the rice. In general, there is a competition on nutrition between the rice and the rice rhizosphere microbes in the rice tillering stage and filling stage. As a result, the activity of rice rhizosphere mi- crobes descends. The microbial biomass C content in rice rhizosphere changed as the rice grows,which differ from enzyme in the rhizosphere. The microbial biomass C, phosphatase, urease, total protein, total phenol content in rice rhizosphere are affected by split N fertilizer application. There is an obvious difference with N and without N treatment in the latest rice growth periods after fulfillment the N fertilizer.