The invention discloses a maritime module drilling rig blowout preventer transshipment device. The maritime module drilling rig blowout preventer transshipment device comprises a transshipment bracket, the transshipment bracket is movably connected to a first translation guide rail, the first translation guide rail is welded to an auxiliary beam of a module drilling rig base, a second translationguide rail is welded to the translation bracket, a slide cart is installed on the second translation guide rail, and a blowout preventer pressure testing pile is arranged at the upper portion of the slide cart. The invention further discloses a transshipment method for utilizing the maritime module drilling rig blowout preventer transshipment device. The transshipment method specifically comprisesthe following steps of installing blowout preventer transshipment and hoisting equipment, hoisting a blowout preventer to the initial position, conducting pressure testing and testing on the blowoutpreventer, installing the blowout preventer, detaching the blowout preventer and moving the blowout preventer to the next well opening. The maritime module drilling rig blowout preventer transshipmentdevice can quickly conduct transshipment and pressure testing on the blowout preventer at the low position, satisfy random transshipment of the blowout preventer in the four directions, is applicableto installation of a platform clump type blowout preventer among well positions, and has the advantages of being simple in structure, facilitating equipment operation and maintenance and being high in safety.