Hydrogen maser is the time and frequency reference source of metrology, punctuality and scientific research in China, and it is the core equipment of national important projects such as deep space exploration, navigation and positioning. In this paper, a scheme to realize the digitization of magnetic field of hydrogen atomic clock is presented. We first design a simple programmable precise current source. And then we use a microprocessor-based intelligent control algorithm to automatically find the maximum power point corresponding to the output voltage of the single-chip microcomputer. Finally, the constant output voltage. In the actual test process, we designed the constant current source circuit output current step quantity can achieve 5uA high precision, spectrum analyzer sampling efficiency and the control system work accuracy is very high.