Abstract: Introduce the study and application of add intensifier to improve many cyclic huff and puff and steam flooding performance. Though the study, we discover that intensifier solution can lower the oil viscosity and oil-water interfacial tension; Add intensifier in hot water can lower the residual oil saturation 4.7%; Add intensifier in steam flooding can improve the sweep volume, increase the oil production rate apparently, and the oil recovery can enhance 17.5%; This technology has been used in field for 37 times, the average period oil-steam ratio has improved 114%, the technology success ratio has been 100%, the accumulative enhanced oil has been 17003.34 t, gained high economic benefit. Based on our study, we discovered that this technology can be used in marginal reservoir which came into later period of huff and puff, inappropriate to general steam flooding.