The mathematical model of a two spool turbojet engine with pulsed fuel supply system was established and considered in this paper.The thrust responses to pulsed fuel supply in main combustor at six flight regimes have been calculated by the use of the established model based on flight test data.The calculated results were discussed and compared with flight test data in detail.The results show that engine thrust in this case drops 77～90% in a short time.This means pulsed fuel supply system has a heavy effect on engine performance.