Rotating detonation engines have higher thermal efficiency and specific impulse than conventional deflagration engines due to detonation of low entropy production. A survey of combustor structures, detonation mode, propulsion performance, thermal measurement and detonation instabilitiy is conducted in the current research. However, there are not enough experimental data and measurement instruments, and rotating detonation makes the reliability design of engines very difficult. Thus, there is a long way for the engine application. Especially, rotating detonation engines can be applied to flame holders and magnetohydrodynamic generators.