A power supply device of a marine magnetometer is arranged on a sunken coupling frame and a glass bead of the marine magnetometer and comprises an acoustic communication releaser, a fusion breaking device, a positioning plate and at least two marine balls, and the marine balls are arranged on the top side of the glass bead and installed and fixed through the positioning plate. A plurality of groups of lithium polymer batteries which are connected in parallel and used for supplying electric energy are arranged in at least one marine ball; magnetometer equipment used for measurement is placed inat least one marine ball. Each marine ball is provided with at least one watertight joint which is conveniently and electrically connected with other marine balls, and the watertight joints on all the marine balls are electrically connected through watertight connecting wires; the acoustic communication releaser and the fusion breaking device are electrically connected with an marine ball with alithium polymer battery through the watertight connecting wire and the watertight joint; through the mode that the power supply part and the magnetometer equipment are separately arranged, the magnetometer is powered for a long time under the ocean condition, and the problem of magnetic field interference caused by power supply to the magnetometer is avoided.