A high-pressure fuel pump actuator used in an engine, which is used in a fuel injection system of an engine, is mounted on between a driving cam and a fuel pump plunger. The pump actuator includes a guide sleeve, a U-shaped holder, and a pin shaft roller set. The U-shaped holder is formed by stamping the steel plate integrally. The guide sleeve uses a special windowing manner. Both ends of the pin shaft do not need riveting. The structure of the present invention has less number of parts and integrated functions, which can notably reduce the entire weight, the inertial force, the friction, and the abrasion. The operation is steady. The efficiency of the engine is improved.