Abstract: Heavy oil is a kind of low-grade oil resource that can solve energy crisis, but its production is a global difficulty. Cyclic steam stimulation is particularly suitable for heavy oil reservoirs which are geologically complex. After multicyclic steam stimulation, however, heavy oil reservoirs are suffered from a series of problems, e.g. reservoir pressure decrease, nonuniform reservoir production and steam channeling. And assistant gas is conducive to solve these problems which occur in the late stage of cyclic steam stimulation. In this paper, the assisting mechanisms, injection-production optimization and innovative application of current cyclic steam assisting technologies were reviewed, including nitrogen, CO₂, flue gas and foam. Then, their advantages and disadvantages were analyzed. Finally, it was proposed to combine nitrogen with CO₂ to assist cyclic steam stimulation, and it was pointed out that the organic combination of downhole steam generator, downhole viscosity reducing unit and nitrogen is the development direction of assisted cyclic steam stimulation in the future. The research results provide the reference for the subsequent technical reserves and innovation.