Articulated laser sensor is a new-fashioned non-contact three-dimensional coordinate measuring instrument based on non-orthogonal axis architecture, which requires the intersection accuracy of laser beams from the left and right units. Therefore, the acquisition of high precision laser spot center is the premise and basis for ensuring measurement accuracy. The spot center-positioning error can be divided into random and system errors. For random error, the edge threshold method is used to eliminate them. For system error, a compensation method based on nonlinear least square fitting is proposed. Based on the straightness error evaluation method, the results of the above positioning and compensation method of laser spot center are compared and analyzed. The results show that the positioning accuracy of the centroid method can be improved to 0.12 pixel using the proposed method. Additionally, the proposed method performs better than other existing methods and satisfies the high precision measurement requirements of articulated laser sensor.