Abstract: The heavy oil reservoir of the Upper Jurassic Qigu formation in Well block J-230 of District No.9, Karamay oilfield is characterized by serious heterogeneity, thin oil layers and low natural energy. As the oilfield development is at the mid-late stage, the oil saturation of the reservoir significantly decreases, the residual oil distribution is complex, the formation pressure is low and there are more and more high water-cut wells, which results in the difficulties of development and sharp decrease of oil production rate and economic benefit. A field test of nitrogen assisted steam huff and puff technology was carried out in 1995 and the results showed that nitrogen injection could replenish formation energy effectively, elongate huff-puff time and improve the development effect of thermal heavy oil recovery. Whereas, because steam channeling is serious in injectors after multi cycles of nitrogen assisted steam injection, experimental studies are conducted on nitrogen foam assisted steam huff and puff and its profile control and flooding. The results show that high-temperature foaming agents with good foaming ability and stability can be used for common heavy oil reservoirs with strong heterogeneity, with which the oil recovery factor can be significantly improved