A three-dimensional numerical simulation of continuous rotating detonation engine(CRDE),which is particularly designed as a coaxial cylinders combustor,was carried out to reveal its physical nature.Numerical results of CRDE's multi-time cycle propagation process agree well with previous experiment qualitatively.Some key problems about CRDE,such as fuel injection,pre-combustion and detonation structure,were also discussed.At last,a propulsion performance analysis about CRDE was made based on a serial of simulation cases.Specific impulses of five different cases about 2200s were given by the present calculation based on the fuel.The mass flux increases linearly with the increase of injection pressure.