The utility model discloses a side entry type blowout preventer transferring device. The device comprises a base, a main guide rail frame and a plurality of lengthened guide rails, one end of the mainguide rail frame is fixed to the base, a supporting rib plate is arranged at the bottom of the other end, main guide rails are arranged on the two sides of the main guide rail frame, and the ends, close to the supporting rib plate, of the main guide rails are sequentially connected and fixed to the ends of the lengthened guide rails and the lengthened guide rails through alignment fixing mechanisms; a transfer trolley slides on the main guide rail and the lengthened guide rail, and a blowout preventer centering mechanism is arranged in the center of the surface of the transfer trolley; a pushing mechanism located below the transfer trolley is arranged in the center of the main guide rail frame. The blowout preventer can be efficiently and stably transferred from the side face of a drill floor at low cost, the blowout preventer can be quickly centered, and the problem that an overlong guide rail is not easy to transport and install can be solved.