The invention provides a degaussing method with reversible magnetic field. Step 1: Set up a field strength conversion control unit between the degaussing coil and the energy storage device in advance, and connect a field strength induction sensor and an information detection sensor to the degaussing coil; Step 2: Send a degaussing signal to the magnetic medium through the degaussing coil for the first second degaussing, and generate a field strength sensing signal in the field strength sensing sensor; step 3: according to the field strength sensing signal, perform field strength conversion through the field strength conversion control unit, and after the field strength conversion, pass The degaussing coil sends a degaussing signal to the magnetic medium again to degauss again: Step 4: Repeat the step 3, and judge whether there is information in the magnetic medium through the information detection sensor, and in the magnetic medium When there is no information, the degaussing coil is controlled to stop sending the degaussing signal.