Undeniably, adjustable power supply has many applications in ion chromatography. One example would be that a safe and stable adjustable power supply is indispensable for the driving part of the suppressor in ion chromatography. However, the traditional design of adjustable power supply suffers from high complexity, leading to its incompetence for practical engineering under the background of the continuous shortage of chips. Therefore, a method for an adjustable power supply module for ion chromatography is proposed and studied. Firstly, the microprocessor is used to output the MCPWM wave to control the output voltage of the flyback transformer. Secondly, the OCADC is used to collect the feedback voltage. Thirdly, the duty cycle of the MCPWM is adjusted using the PID algorithm to achieve constant voltage output. Further, hardware overcurrent protection is realized through MCPWM fast interrupt function. By this method, an adjustable power supply with a wide voltage output range, high current, and low voltage ripple can be output with less chip resources. Both the theoretical design scheme and the specific hardware circuit of this design is presented. Moreover, a simulation verification analysis is made. Finally comes the verification of the feasibility of this method.