Abstract: The pH meter verification instrument serves as a metrological standard device for the verification and calibration of the electrometric components of instruments such as pH meters, ion meters, and automatic potentiometric titrators. It plays an important role in the field of electrochemical metrology. Despite the release of JJG 919-2023 "Verification Regulation of pH Meter Verification Instruments," there is still no provision regarding the uncertainty evaluation of resistance measurement results for high-value resistors in pH meter verification instruments. This article evaluates the uncertainty in resistance measurement results of high-value resistors in pH meter verification instruments by applying internationally recognized uncertainty evaluation methods: the Guide to the Expression of Uncertainty in Measurement (GUM) method and the Monte Carlo Method (MCM). Firstly, we use the GUM method to assess the measurement uncertainty of the high-value resistors. Then, we employ MCM Alchimia software to evaluate the measurement uncertainty using the MCM. To verify the effectiveness of MCM Alchimia software for the MCM, we compare the calculation results obtained from MCM Alchimia with those from MATLAB software, which offers more comprehensive computational and visualization capabilities, using both the standard MCM and the adaptive MCM methods. The results indicate that the uncertainty outcomes calculated by MCM Alchimia software are consistent with those obtained through MATLAB programming. Furthermore, following the procedure in JJF1059.2-2012 for validating GUM method results using the MCM, we assessed the applicability of the GUM method for evaluating the uncertainty in resistance measurement results of high-value resistors in pH meter verification instruments and found that it failed to pass the validation. Therefore, applying the MCM and utilizing MCM Alchimia software provides a reference for standardizing the uncertainty assessment methods in resistance measurements of high-value resistors in pH meter verification instruments.