Abstract: A simplified model of Pulse Deotonation Engines(PDEs) isadopted in present paper to estimate the system performance withthermodynamic cycle analysis method. The analytical expression of PDE'sthermodynamic cycle efficiency is derived in relation to the parameter oftotal pressure recovery coefficient. In addition, we attempt to investigatethe influence of the total pressure recovery coefficient of PDE inlets andinitial temperature of combustion chamber on the PDE thermodynamic cycleefficiency. The results demonstrates that, reducing total pressure loss ofthe inlets is beneficial to increase the thermodynamic cycle efficiency, andincreasing the initial temperature of combustion chamber can even apparentlyenhance thermal efficiency. Based on the current results, Multistage PulseRe-Detonation Engines(MPRDEs) configuration is presented in this paper forthe first time. We use the shockwave front of detonation waves decoupled atcorner to compress the working medium, which improves the thermodynamicalparameters of the working medium and PDE's system performance. Thethermodynamic cycle efficiency of this configuration is derived, whichdemonstrates the possibility of MPRDE configuration theoretically. Theresult shows that, MPRDE configuration can improve the thermal efficiencyeffectively via raising working medium's temperature in front of detonationwave. Finally, because some of the working medium is not perfectly expandedwhen rushing out of nozzle, a qualitative discussing is carried out on PDE'sthermal efficiency under different exit pressures. The moment of workingmedium will be promoted and thermal efficiency will be improved when theexit pressure is lowered.