The invention provides a three-phase coaxial superconducting cable-to-three-core superconducting cable switching device and a switching method, belonging to the technical field of superconducting cable switching. The device comprises a box body with a three-phase coaxial superconducting cable interface and a three-core superconducting cable interface arranged oppositely; the side wall with the three-core superconducting cable interface is provided with a three-core superconducting cable reflux pipe interface; the bottom of the box body is fixedly provided with a supporting plate, and the top of the supporting plate is uniformly and equidistantly provided with three-phase wiring positioning ports and a Dewar pipe drainage port opposite to the three-core superconducting cable reflux pipe interface; the three-phase coaxial superconducting cable interface and the three-core superconducting cable interface have the same height; and the height of the three-core superconducting cable reflux pipe interface is lower than that of the three-core superconducting cable interface. Stable physical electrical spacing is formed, accidents such as net distance reduction and discharge and joint damage due to external shock and the like can be avoided, a sufficient electrical distance is kept between the fluid connection pipe and three-phase electrical connection, short circuit or discharge accidents can be prevented, and the use is safe.