Abstract: Affected by structural development frame of the Xihu Trough, Chunxiao Structure underwent rift, depression, and regional subsidence three development stages and appeared as two phase super-imposed anticline. Chunxiao boasted several sets of good source rock. Depositional facies research showed that excel-lent source-reservoir-caprock assemblage in Chunxiao area. Inversion resulted that the anticline trap directly overlaid on the sag. The uplift made hydrocarbon expelled from source rock and accumulated to the upper trap, this maybe the main mechanism of hydrocarbon migration. Inversion after structural subsidence, that is, Oligocene to Miocene, is the main migration and accumulation phase.