In order to measure the center position and radius of laser spot accurately, a laser spot center locating method was proposed based on Vision Assistant of the LabVIEW visual processing module. Under the Matlab environment, 3 common spot center locating algorithms were adopted for simulation of the pretreated laser spot images collected by CCD camera. And contrast experiments were made with the method, including the comparison of Houng transformation with its improved scheme, the comparison between different operators of circular fitting method, and the comparison of the two-time refining of spatial moment localization method. Analysis was made accordingly to the advantages and disadvantages of the 3 locating algorithms. Finally, different Regions of Interest(ROIs)were taken randomly, and averaging was made to multiple measurements. The simulation results show that the improved scheme can get the spot center position and the radius quickly and accurately.