In ordered to realize dynamic simulation of working process in the rotary engine, a spark-ignition rotary engine is chosen as the research object, the detailed calculated models have been established including combustion model and turbulence model. With numerical simulation, same important information in the cylinder is obtained, such as the velocity, temperature fields and flame propagation. Furthermore, the effect of pocket location on the flame propagation is analyzed. The results show that under the calculating condition, when the pocket is located at the rear of rotor, the rate of combustion and the peak pressure are better than that of other cases, and NO emissions increases accordingly. This study provides some theory guidance for the determination of best pocket location under different working conditions.