The reservoir-forming mechanism was studied by analyzing 17 oilfields and 69 blocks in the Jiyang depression statistically and by anatomizing 5 blocks typically，and then the reservoir-forming difference of stratigraphic reservoir was analyzed. The results show that opening and sealing properties of oil source fault control the directions of oil and gas migration；positive tectonic background controls the stratigraphic reservoir enrichment；unconformity structure controls the stratigraphic reservoir types，and reservoir-forming dynamics controls the hydrocarbon potential of the stratigraphic trap. The mi? gration mode along oil source fault for basin margin stratigraphic trap in Jiyang depression are mainly lateral，vertical as well as along the strike. The stratigraphic reservoirs with different mode of hydrocarbon migration are different in scales.There are also differences in reserves due to different types and entrapping horizons of stratigraphic traps. The reserves of stratigraphic reservoirs in Neogene Guantao group and the stratigraphic overlap reservoirs are the largest. There are differences found in stratigraphic reservoirs developed at the same type of structural belts in different sags or at different structures in the same sag. There are overlap reservoirs and truncation unconformity reservoirs in the gentle slope belts，the reserves scale of which are larger with little difference. In the steep slope，there are mainly overlap unconformity reservoirs.