Abstract: Steam soak is mainly used to develop super-heavy oil reservoir. With the increase of circulation turns, formationpressure and periodic oil production decrease rapidly, and production effect is poor. This paper builds a theoretical model withintegration of geological characteristics of Jiu 7+8 block in Xinjiang. Then by numerical simulation, it analyzes the feasibility to injectnitrogen at late stage of steam soaking and optimizes the key parameters of mixed nitrogen ratio, injection timing, injection mode,injection rate and so on. Simulation results show that average periodic oil production of single well after nitrogen injection increases6146.9 ton，water cut decreases 15%. To inject nitrogen during steam soaking can improve development effect of super heavy oilreservoirs to a great extent, and provide reference for development of similar difficult-to-produce reserves.