本文分析了ＰＳＤ的非线性成因，并根据ＰＳＤ的非线性特点，提出了一套预先离散标定，再运用双一次插值算法或双二次插值算法对ＰＳＤ的非线性进行了一定补偿，从而使ＰＳＤ的Ｂ区获得了与Ａ区近似的线性度，故在不增加成本，不改变测量设备的复杂度的情况下，扩大了测量范围，提高了Ｂ区的测量准确度及数据的置信度。 This paper analyzes the PSD non-linear causes, and according to the nonlinear characteristics of PSD, proposed a set of pre-discrete calibration, and then use double or double quadratic interpolation algorithm to compensate for the non-linearity of PSD, so that the PSD Area B obtains a linearity similar to that of area A, thus expanding the measurement range without increasing the cost and without changing the complexity of the measurement equipment, thereby improving the measurement accuracy and the confidence of the data in area B.