Abstract: The characteristics ot oil and gas migration and accumulation and the general rules regarding the formation of large oil fields in China's continental basins are the main subjects of discussion in this paper.Short distance lateral migration of oil and gas is the general rule,though vertical migration and multi-stage accumulation and dispersion are not uncommon.The height of vertical displacement controls the upward migration of oil and gas,and primary oil pools are formed in the lower part of the main faults and secondary pools in their upper part.In our continental basins,there are three types of oil pools with: oil generated and reservoired in rocks of the same age,oil generated in young source beds but reservoired in old rocks and oil generated in old source beds but reservoired in young rocks.The prerequisites for the occurrence of a large oll field are: an oil generation sag,a large trap,a large sand body (or sindlar reservoir),an unconformity surface and a large contemporaneous fault.