Aiming at the high-power electromagnetic field excitation needs of electromagnetic detection, this paper adopts a cascaded rectifier power supply with input in parallel and output in series to increase the output voltage level and ensure the excitation power. In order to satisfy the stability of output current, a constant current and voltage equalization control algorithm based on double closed loops was proposed. The principle of constant current and voltage equalization of cascaded DC power supply was analyzed, the mathematical model of the power supply was established, the voltage and current loop controller was designed, the simulation model was built in Matlab/Simulink and the controller parameters were optimized to reduce the error. Because the upper and lower parts of the cascaded DC power supply may have different device parameters, this leads to different output voltages of the two power supplies under constant current control, and the deviation was greater under dynamic conditions, which caused damage to the device due to uneven voltage. Therefore, it is necessary to add the control voltage equalization output while considering the control of the constant current output. By sampling the output current and voltage, the controller converted it into the corresponding pulse to trigger the corresponding switching device to realize the constant current and voltage equalization output. The simulation results showed that the output current is controlled at 2 A, and the current change is below 5%.