Abstract: Sandstone lens pools are endued with a superior setting of hydrocarbon accumulation for being adjacent to source rocks,but the mechanism of hydrocarbon accumulation is far more complex that that of the structural hydrocarbon reser- voir.Dynamic forces and resistances are summarized from the points of the connotation of sandstone lens and its mech- anism of storing hydrocarbon.Only when the dynamic forces are greater than the resistances of hydrocarbon accumula- tion,the hydrocarbon can break through the critical value of accumulation threshold to generate the oil and gas pool.The matching relationship between the factors of hydrocarbon formation and the dynamic forces of hydrocarbon accumula- tion destines the hydrocarbon formation as stage by stage. The filling extent of sandstone lens pool is subject to the thickness and quantity of source rocks,structural position, sedimentary type,burial depth,physical properties of reser- voir bed and the thickness of sandstone body.In the area where hydrocarbon source is superior,the key factor of the filling extent of sandstone lens trap is the migration setting.