Single-shot pulse detonation engine (PDE) with three different types of nozzles-straight ejector combinational structures at three different ejector positions were simulated by the unsteady 2-D axisymmetric method. Three types of nozzles included the straight nozzle, convergent nozzle and convergent-divergent nozzle. Propane was used as the fuel and air as the oxidizer. The simulation results indicated that the PDE with a straight nozzle and PDE with a convergent-divergent nozzle obtained improved performance when an ejector was added at all of the three ejector positions (x /d = –1, 0 and +1), and PDE with a convergent-divergent nozzle gained the larger improved performance at all the three ejector positions. The PDE with a convergent nozzle-ejector combinational structure obtained the slightly worse performance at the ejector position of x /d = –1, gained the slightly increased performance at the ejector position of x/d = 0, and achieved the largest impulse augmentation and the second largest ejection ratio at the ejector position of x /d = +1 among all of the nine cases of the nozzle-ejector combinational structures. Ejector position of x /d = +1 was the best ejection position at which the PDE with a convergent nozzle-ejector combinational structure achieved the best propulsion performance, ejector position of x /d = –1 was the best ejector position for the PDE with a convergent-divergent nozzle-ejector combinational structure, and ejector position of x /d = 0 was the best ejector position for the PDE with a straight nozzle-ejector combinational structure.