The invention discloses a plug valve. The plug valve comprises a valve body, a valve plug, a bottom cover, an upper cover, a motor, a sliding block, a control rod, a roller and a connecting rod mechanism; a valve body through hole is formed in the valve body; the valve body through hole comprises a slim hole, a cone frustum hole and an enlarging hole from the top to bottom; the valve plug consistsof a connecting rod, a valve plug main body and a sliding rod from the top to bottom; the bottom cover is fixedly connected with the lower end of the valve body and is used for sealing the enlarginghole; the upper cover is fixedly connected with the upper end of the valve body and is used for sealing the slim hole; the motor serves as a stepping motor and is mounted on a mounting frame of the upper cover; the sliding block consists of the mounting frame, a sliding plate and a hinged pin; the control rod consists of a large-diameter end and a small-diameter end; a roller through hole is formed in the roller; and the connecting rod mechanism comprises a short connecting rod and a long connecting rod. The plug valve is simple and reasonable in structure, long in service life and convenientto control.