A combined type linear motion device comprises a linear sliding block portion, a guide structure portion and a drive portion. The linear sliding block portion comprises a sliding rail, a sliding blockand a platform. The sliding rail is of the linear type. The sliding block penetrates through the sliding rail and is connected with the sliding rail in a mutually matched manner. The upper portion ofthe sliding block is a horizontal plane and is horizontally attached to and fixed to the platform. The drive portion comprises a motor and a synchronous belt pulley. The motor is vertically and downwards arranged on the upper surface of the platform. An extending-out shaft of the motor penetrates through the platform and extends to the lower end to be fixedly connected with the synchronous belt pulley. The guide structure portion comprises an L-shaped steel plate and a synchronous belt. The L-shaped steel plate is parallel to the sliding rail. The synchronous belt is a rectangular belt. The synchronous belt covers and is fixed to the upper portion of the surface of the side, far away from the sliding rail, of the long edge of the L-shaped steel plate in parallel. The surface of the outerside of the synchronous belt is evenly provided with arc teeth. The positions of the arc teeth allow the arc teeth to be meshed with the synchronous belt pulley. The combined type linear motion deviceis convenient to install, low in maintenance cost, lower in wear degree, longer in service life and convenient to clear, and the synchronous belt has the damping function.