Resistance source device capable of achieving precise output of power

The utility model relates to a resistance source device capable of achieving precise output of power. The resistance source device capable of achieving precise output of power comprises a magnetic metal rotary disc, wherein the magnetic metal rotary disc is fixed on a support and is connected with a power source. A magnetizer with a groove opening is further fixed on the support and is provided with an electromagnetic coil, wherein the edge of the metal disc is sleeved by the groove opening of the magnetizer, and the electromagnetic coil is connected with a magnetic force control circuit. The magnetic force control circuit comprises a microprocessor and an electromagnetic drive circuit, the microprocessor is connected with an upper controller through a port, the microprocessor outputs a pulse-width-adjustable signal and is connected with the electromagnetic drive circuit, and a rotary disc speed feedback sensor is arranged on the support and is connected to the signal receiving end of the microprocessor in a