Abstract: The method of Lissajous figures is usually used in measuring pulse linearity of photoelectricity multiply tube (PMT). In view of bigger uncertainty of Lissajous figures, this study proposes that constant current calibration may be used to determine standard line of Lissajous figures, accurately determine the pulse linear range of PMT. The study also provides an application example which indicates that this method effectively reduces uncertainty rooting in judgement of standard line and enhances accuracy of measurement.