The structure of cambermeasurement system is p resented at first. Method of subp ixel location based on 2nd spatialmoment operators is deduced. Then the center of laser spot ismeasured at high accuracy. Edge of laser spot is reached at p ixel accuracy using LoG operators, it is reached at subp ixel accuracy using 2nd spatialmoment operators, and the center of laser spot can be gained by fitting. Contrastive experiments have been conducted to test usualmethods and the method of 2nd spatialmoment operators, and a quantitative analysis of results is carried out. The experimental results show that subp ixel location of the center of laser spot based on 2nd spatial moment operators is much better than usual location operators.