The invention relates to the technical field of electrical equipment, particularly a power grid direct supply-based high-power pulse power supply. The high-power pulse power supply comprises a 24-pulse wave uncontrollable rectifier, three-phase triple chopped wave units and a reversing unit, wherein the 24-pulse wave uncontrollable rectifier is used for converting the three-phase alternating current mains supply into three paths of direct current to be output to the three-phase triple chopped wave units; each three-phase triple chopped wave unit is corresponding to one path of direct current output of the 24-pulse wave uncontrollable rectifier, and used for converting the instable direct current voltage into a stable direct current voltage needed by a load and outputting the stable directcurrent voltage to one reversing unit separately; and the reversing unit is used for realizing reversing of positive and negative directions of the output current and outputting to a demagnetizing coil. By virtue of the high-power pulse power supply, the problem of current waveform distortion input on the grid side is solved, and the waveform quality of the output direct current voltage is ensured. Meanwhile, compared with a silicon controlled rectifier for rectifying, the 24-pulse wave uncontrollable rectifier improves the power factor of the apparatus, and in addition, direct current stability of a subsequent device is also ensured.