The invention aims to provide a pre-mixing type pulsed abrasive gas-jet erosion method and device. The device comprises a gas compressor and a gas storage tank connected with the gas compressor, wherein the gas storage tank is connected with the bottom of an abrasive tank through a gas inlet tube; a discharge hole is formed in the top of the abrasive tank; the discharge hole is connected with a charge branch tube of a gas exhaust tube through an impeller type discharge mechanism; one end of the gas exhaust tube communicates with the gas inlet tube between the gas storage tank and the abrasive tank; and the other end of the gas exhaust tube is equipped with a spray nozzle mechanism. The pre-mixing type pulsed abrasive gas-jet erosion device is simple in structure, is delicate in design, can utilize pulsed abrasive gas jet flow to erode a target body, so that a better abrasive erosion effect is formed.