The invention discloses a pressure linear adjusting combined nozzle and a high-pressure cleaning device. The combined nozzle comprises a high pressure nozzle body, a sliding valve and a head shell, wherein the high pressure nozzle body is provided with a center spraying channel; the sliding valve is provided with a water passing hole; the head shell is provided with a cavity penetrating the frontend and the rear end of the head shell and containing the high pressure nozzle body and the sliding valve; the sliding valve is arranged behind the high pressure nozzle body in a sliding manner; the outer wall of the sliding valve and the cavity wall of the cavity form sliding sealing; a bypass path is formed between the outer wall of the high pressure nozzle body and the cavity wall of the cavity; the rear end of the center spraying channel is provided with an inner cylindrical face; the front end of the sliding valve is provided with an outer cylindrical face capable of forming sliding sealing with the inner cylindrical face; and the outer cylindrical face is provided with at least one aerial drainage groove, the section area in the radial direction becomes large from the rear to the back or in a nearly linear manner, and the aerial drainage groove extends to the front end of the outer cylindrical face. The pressure linear adjusting combined nozzle has the beneficial effects that high and low pressure adjusting can be more accurate and smoother, the cleaning capacity of the equipment is improved, and besides, it can be avoided that because of the insufficient water pressure, water dripping of an outlet is caused.