Abstract: This paper reviews the principles and primary characteristics of Pulse Detonation Engine (PDE),the prospect of its application and trends of its development.The results of our recent theoretical,experimental and numerical researches of pulse detonation engines are summaried.The experiments of a two phase PDE with three different diameters were carried out successfully.The gasoline/air mixture was used in the PDE.The ignition frequency can vary in the range of 5～117 Hz.The ignition energy of the spark igniter used in these experiments is approximately 50 mJ.The PDE research areas,key technology and development stages in 21 century are foreseen.