The working principle of four-quadrant position sensitive detector(4Q-PSD) as a spot center position measurement detector is presented. Influence of the photoelectric non-uniformity of detector and background light on the detector measurement precision is analyzed. The operational circuit to solve the relationship of spot center position in the coordinates of detector and detector output voltage is designed. And the detector performance testing system based on laser alignment measurement is developed. The relationship between the output voltage of detector and the spot center position in the coordinates of detector is tested. The linearity of output voltage and spot center position in the uniaxial direction of the detector within a small range is good. The influence of measurement distance on the accuracy of the detector is tested. Method of 2-D plane calibration of the 4Q-PSD is proposed, and the detector is 2-D plane calibrated using proposed method. Which extended the available working range of the detector, and with higher measurement accuracy.