Disclosed is an electric greasing device capable of controlling grease quantity. A piston is arranged inside a hydraulic cylinder, two ends of the hydraulic cylinder are provided with a sealing cap and an end cap respectively, the right end of a screw rod is connected with a piston through a fixing nut, the left end of the screw rod is arranged in a sleeve, the right end of the sleeve is positioned in the hydraulic cylinder, a rolling bearing is sleeved at the right end of the sleeve, the left end of the sleeve penetrates through the sealing cap, extends out of the hydraulic cylinder and is connected with a transmission pinion through a key, and the transmission pinion is engaged with a main transmission gear arranged on an output shaft of a speed reducer. A servo motor is used for driving the screw rod and the piston to squeeze lubricating greases, the grease outlet quantity is adjusted by adjusting the rotation speed of the motor, a microscopic quantity of greases can be filled, and the greases can be filled rapidly. Gear transmission is adopted, torque is increased, sufficient driving force for driving the piston to move is ensured, force transfer is stable, grease outlet uniformity and continuity are ensured, and the electric greasing device is particularly suitable for experimental test of the performance of lubricating greases.