The invention provides a recovery system and a recovery method of residual pressure and residual heat in a backpressure heat supply unit. The system and the method can reduce loss if water, heat and pressure energy, increase heat supply of the backpressure heat supply unit and eliminate a phenomenon of 'generating white smoke'. The system comprises a backpressure steam turbine, a deaerator, a drain tank, a drain flash tank, periodic blowdown flash tank, valves from No.1 to No.7, a steam jet pump, a main pipeline and a bypass pipeline. In normal operation, the No.3 valve and the No.4 valve areclosed, and other valves are opened; discharged steam of the backpressure steam turbine is conveyed into the steam jet pump to be used as working steam, thus, after the steam jet pump extracts the discharged steam in the periodic blowdown flash tank, the drain flash tank and the drain tank, pressure is reduced and the steam becomes medium pressure steam usable for the deaerator, and the medium pressure steam enters into the deaerator; if the steam jet pump goes wrong, the No.3 valve and the No.4 valve of a bypass line are opened, and the No.1 valve and the No.2 valve are closed, the system cancontinue working, and thus continuous running of the system is guaranteed.