Abstract Considering the problem of measuring the peak junction temperature of a double-chip module with temperature inhomogeneity, we use a double-chip parallel model to analyze peak junction temperature measurement error for the traditional electrical method. An improved test method is proposed that is based on the small current–voltage drop method—specifically the dual current test method employing an extended-dimension calibration curve library. This method realizes a match of the calibration current with the test current by expanding the dimension database, eliminates errors of temperature measurements, and finally obtains the peak junction temperature of the module. The measurement result is close to the set temperature of the model, thereby verifying its accuracy.