Abstract: The pulse linear current of PMT is an important parameter, which is related to the reliability of experiment data. Contrasted some methods of measuring PMT’s pulse linear current, focusing on improving precision of measurement, an experiment method based on double pulse method was designed for measurement. The details of method were designed for improving precision, such as using stability LED light as light source, suppling LED voltage by DG2020 signal generator, increasing interval of signals by using “making sequence” function of DG2020, recording one PMT’s output on two oscilloscopes by segregator and using average function of oscilloscopes. The pulse linear current of PMT, where output current departures 1% from linear curve, was measured by this method. The whole curve of PMT pulse output current was obtained.