A gas-liquid mixing type jet flow jetting device comprises a first mixing cavity part (1), a second mixing cavity part (2), a conical reducing part (3) and a diffusion part (4) which are sequentiallyand adjacently connected, one or more gas suction inlets (7) are formed in the circumferential direction of the first mixing cavity part, and a water inlet (5) is located in the center of the first mixing cavity part; one or more treatment liquid inlets (9) and compressed gas inlets (10) are formed in the circumferential direction of the second mixing cavity part (2); the flow regulating valve ischaracterized in that a plurality of flow regulating pieces (12) are arranged on the inner circumferential wall of the conical reducing part (3), a buffer cavity (16) is formed in each flow regulatingpiece, one or more inlet holes (17) are formed in one side of each flow regulating piece, and one or more outlet holes (18) are formed in the other side of each flow regulating piece. According to the gas-liquid mixed type jet flow jetting device, the problems of liquid impact and liquid wall attachment during confluence of the conical reducing part can be reduced, the design of the buffer cavitycan properly increase the pressure of liquid in the cavity of the conical reducing part during confluence of the liquid, and a certain pressurizing effect is achieved.