The linear electric cylinder adopts modular design method and integrates elements such as servo motor, servo drive, high precision ball screw, etc. The whole electric cylinder has the features of compact structure, small inertia, fast response, high rigidity, low noise and long service life, etc. The servo motor is directly connected to the electric cylinder drive screw, so that the encoder of the servo motor directly feedbacks the displacement of the electric cylinder piston rod. The servo motor is directly connected to the drive screw of the electric cylinder, so that the encoder of the servo motor directly feeds back the displacement of the piston rod of the electric cylinder, which reduces the inertia and clearance of the intermediate link and improves the controllability, control rigidity and control accuracy. The servo motor is connected to the electric cylinder as a whole, which is easy to install, simple to set and convenient to use.