Based on study of base level changing, the control effect of sandbody development is analyzed. It is thought that the base level changes frequently during Es3 Member deposition with changing rate of more than 1 000 times/Ma, which leads to the thickness thinning of single sand layer in Es3 Member and frequent alternatinn of sandstone and mudstone. The fourth sequence intertiiee controls the reservoir obviously. So the sandstones near the inter-well develop and the hydrocarbons enrich, which are the targets for oil gas exploration.