Needle valve lift-adjustable fuel injector assembly

The invention belongs to the field of an oil supply system of a diesel engine, and particularly discloses a needle valve lift-adjustable fuel injector assembly. The needle valve lift-adjustable fuel injector assembly comprises a fuel injector body which has a fuel inlet at the upper part, and is characterized in that the lower end of the fuel injector is connected with a needle valve body, a tightening cap which is threaded with the fuel injector body is sleeved outside the needle valve body, a small excircle of the needle valve body extends out of the tightening cap, a tail-free needle valve is slidably arranged in the cavity of the needle valve body, a transition plate is arranged between the fuel injector body and the needle valve body, a central hole which penetrates through a mandril and a stepped hole which limits the needle valve lift are arranged on the transition plate, bores for communicating with an oil inlet are arranged on both the transition plate and the needle valve body, and an oil return por