In the course of exploration and practice for offshore oilfield steam huff and puff, for the restriction of reservoir conditions, drilling mode, platform space as well as operational cost, the application of steam huff and puff for offshore oilfield is more difficult than onshore oilfield. Chemical enhanced steam huff and puff could expand swept volume, improve swept factor, decrease the viscosity of heavy oil, thus improve development effect. This article mainly discusses and evaluates the effect of recovery and economy for this technology from mechanism, laboratory physical simulation and numerical simulation base on actual geologic model of some Bohai oilfield . The results shows the oil production is improved by 16% on the basis of conventional steam huff and puff after 7 cycles of chemical enhanced, the input-output ratio is up to 1:6.3(oil price by $40 / barrel). This technology lays a solid foundation for deepening thermal recovery and affords new methods for offshore oilfield heavy oil high efficiency development.