To improve the calibration effect on battery open-circuit voltage, a proton exchange membrane is introduced in this paper to design a battery open-circuit voltage calibration method. A novel open-circuit voltage calibration method for proton exchange membrane fuel cell (PEMFC) is studied. Its working principle is analyzed, and its open-circuit voltage is expressed by the Nernst equation. During the calibration process, a calibration device is connected to the measurement point. The PEMFC sheet is placed on the separator, and the open-circuit voltage is measured by an I-V meter in the separator and the calibration device simultaneously. Based on the comparison of two groups of non-measurement data, the calibration coefficient is obtained. According to factors affecting the open-circuit voltage of PEMFC, the uncertainties in the calibration due to the introduction of irradiance deviation in the simulator, temperature control deviation, and repeatability of measurement instruments are analyzed. Experimental results show that compared with the contrast method, the average calibration error of the proposed method was more than 50% lower and the corresponding average calibration time was 1.77 s shorter, indicating that it can achieve high-precision and high-efficiency PEMFC open-circuit voltage calibration.