The invention discloses a composite mechanism full flow circulation supersonic velocity propulsion system and a working method thereof. The system comprises an air admission passage, an air compressor, a diffusion duct, a shaft, an open type pre-burning driver, a closed type pre-burning driver, a turbine, an afterburning thruster and a jet nozzle; the air admission passage, the air compressor, theshaft, the turbine, the afterburning thruster and the jet nozzle are sequentially connected; the air compressor is connected with the turbine through the shaft; the turbine is positioned on the air inlet side of the afterburning thruster; the jet nozzle communicates with the outlet of the afterburning thruster; the open type pre-burning driver and the closed type pre-burning driver are positionedbehind the air compressor, and outlets directly face the turbine; and the open type pre-burning driver and the closed type pre-burning driver are alternately distributed in the diffusion duct in an annular space on the outer side of the shaft. The system gives play to propulsion advantages of all subsystems in the aspects of specific impulse and thrust-weight ratio as much as possible, so that asupersonic velocity combined propulsion system which is rapidly started by self, has multiple degrees of freedom and composite working mechanism and is efficient and economic is realized.