Abstract: In order to overcome the shortcomings of traditional subpixel location algorithm, such as weak anti-jamming ability, poor positioning accuracy, and difficulty in software realization, and improve the center location accuracy of laser spot, the method of curve fitting was used and a high-precision positioning measurement method of small spot size was proposed. After theoretical analysis and experimental verification, the error of center-of-mass extraction is controlled within 0.1pixel. The results show that the image centroid measurement method reduces the noise interference effectively and enhances the anti-noise performance. Compared with the traditional algorithm, the error is smaller.