Disclosed is a hybrid propulsion system, comprising an engine, a first motor, a second motor, a power coupling device and a drive shaft. The power coupling device includes a first propeller shaft connected with said engine via a first clutch, a second propeller shaft connected with the rotor of said first motor, and a third propeller shaft connected with the rotor of said second motor. By a planetary gear mechanism with an inner ring gear, said first propeller shaft, said second propeller shaft and said third propeller shaft come into driving engagement with one another. Said inner ring gear and said third propeller shaft are individually selectively in driving engagement with said drive shaft.