The invention discloses a fuel injection pump. The fuel injection pump comprises a fuel inlet base and a fuel outlet base, wherein the fuel inlet base is connected with the fuel outlet base through a pump body, and the pump body is also connected with a plunger; the plunger is coaxially arranged in a pressure cavity, the fuel inlet pipeline of the fuel inlet base is communicated with the pressure cavity, the fuel outlet base is arranged at one outlet of the pressure cavity, a fuel capacity control sleeve is sleeved on the plunger body, one end of the fuel capacity control sleeve is movably arranged in a tappet body, and a plunger spring is arranged between the fuel capacity control sleeve and the tappet body; the fuel outlet base comprises a fuel outlet control valve, and a pressure regulating structure is arranged between the fuel outlet control valve and a fuel outlet. Through the arrangement, the fuel injection pump has the advantages that the structure is simple, the operation is convenient, the dismounting is convenient, the cleaning is convenient, the prolonging of the service life is facilitated, and the reliability of the fuel injection pump is improved.