The invention discloses a high-pressure vapour sterilization method of a mushroom stick. The method comprises the steps that (1),the mushroom stick is punctured, a breathable film is bonded to the mushroom stick, and the breathable film is sealed after the mushroom stick is placed in a high-temperature sterilization device; (2), vapour is added, an air inlet valve is adjusted to a lower magnitudewhen the pressure is increased to 0.9 kg / cm <2>, an air discharging valve is switched on gradually, the air inlet valve is completely switched on when the pressure drops to zero, the state of the airinlet valve is maintained for 3-5 min until dense vapour is discharged out from an air discharging port, the air discharging valve is switched off, and the air discharging operation is repeated; (3),when the vapour pressure is increased to 0.8 kg / cm <2> and the temperature is increased to 108 DEG C + / - 1 DEG C, the air inlet valve is adjusted to stabilize the pressure and the temperature, and the pressure and the temperature are maintained for 4 hours; (4), the vapour pressure is adjusted from 0.8 kg / cm <2> to 0.4 kg / cm <2> within 0.8-1 hour, the temperature is 105 DEG C + / - 1 DEG C, andthe pressure and the temperature are stabilized for 5 hours; (5), the air inlet valve is switched off, the air discharging valve is switched on when the vapour pressure is naturally reduced to 0.1 kg / cm <2>, the air discharging valve is switched off when no vapour is discharged from the air discharged valve, and the sterilization is completed.