The invention is refer with an electromechanical stretching apparatus of a convertible sofa, which consisting of a mechanical stretching apparatus and an electric actuator, the mechanical stretching apparatus being provided with an electrically-driven connecting rod, wherein, the electric actuator consists of a motor, a motor connecting tube, a motor movable slider, and a motor head fixing part, the motor adopted is a motor with a guide rail, the motor movable slider is installed on the guide rail of the motor, the motor head is rotationally connected through a second rotor shaft to the motor head fixing part fastened on the electrically-driven connecting rod, the motor connecting tube is connected to the motor movable slider through a first rotor shaft and the motor connecting tube is fastened on the mechanical stretching apparatus. The said motor connecting tube is fastened on a linkage part of the mechanical stretching apparatus. The said first rotor shaft and the second rotor shaft are both a bolt. By changing the electronic driving device, the invention increases automaticity and comfort of the convertible sofa, and improves installation, removal, maintenance, and operation efficiency of an electric actuator of the convertible sofa.