A side transfer design method is proposed to solve the problem that docking is achieved by floating and sinking methods. Design the starboard wing walls as removable, secure the removable wing walls to pontoon deck with easy operated pin type device, and connect the wing walls with the ballast tanks in pontoon area by the rubber-seals. Arrange the square railways on pontoon deck along the transverse direction of the floating deck, lift away the removable wing wall before the vessels be transferred into the dock transversely, and adjust the railways on pontoon deck in line with the railways on the shore by rigidity mooring system and the railway connecting bridges, then transfer the vessels into the floating dock transversely by translation cars. The design floating docks has been delivered and the side transfer has been also put into service successfully. The design method is effective for side transfer, which can provide some references for the other side transfer design of this kind of floating docks.