Abstract: The principle, structure and property of optoelectronic position sensitive detector (PSD) are briefly introduced. The nonlinearity caused by PSD is analyzed according to the principle and characteristics of PSD. The location equation of PSD output signal independent of light intensity was derived. PSD nonlinearity modulation circuit was designed to achieve low temperature drift and high precision. The validity of correcting PSD nonlinearity with differential algorithm, optimization method of neural network and analytic method is analyzed. Some of the data obtained during the experiment are also analyzed. The prospects of PSD′s application in optical trigonometry, automatic check and highprecision measurement are discussed.