The invention discloses a mechanical-hydraulic servo cylinder. The mechanical-hydraulic servo cylinder comprises a cylinder body, a piston rod, a cylinder bottom, a cylinder head, a motor, a hollow screw rod, a valve core, a valve sleeve, a guide sliding block, an oil return port, an oil inlet, an oil way communicating with a rear cavity, and an oil way communicating with a to-be-distributed area.The motor rotates to drive the hollow screw rod to rotatably move to drive the valve core to make linear movement, a valve opening is opened, the piston rod moves following the valve core under the effect of the pressure of hydraulic oil and forms a closed loop with the opening degree of the valve opening, and in this way, the movement direction, speed and position of the piston rod are controlled by only needing to control the rotating direction, rotating speed and rotating angle of the motor.