The invention relates to the field of electronic element material preparation, in particular to an automatic magnetic powder punching device. The automatic magnetic powder punching device comprises a transmission belt, a fixing frame, a power air cylinder and a punching disc; the fixing frame which is a door-shaped frame is arranged on the conveying belt; the power air cylinder is fixed on a cross beam of the fixing frame; the punching disc is fixedly connected with an extensible rod of the power air cylinder; the punching disc comprises a disc surface and a punching rod; the disc surface is provided with a plurality of isometric array installation holes; the punching rod penetrate the installation holes and can relatively slide; the punching rod and the disc surface are fixedly connected through a spring; the end portion of the punching rod is provided with a cross punching head; a vertical pile of the fixing frame is provided with an optical fiber sensor which is used for detecting a mineral powder box. The automatic magnetic powder punching device has the advantages of achieving automatic loosening of mineral powder, saving manual costs, being uniform in punching and not easy to collapse, enabling the mineral powder to be fully oxidized during roasting and achieving the product percent of pass.