In the visual survey,measuring error is existed inevitable between observed value and real value.How to reduce measurement error becomes the key problem that needs to be solved in precision measurement,particularly in the high precision measurement system.GSI coding point was taken as an example,and the centroid localization algorithm of GSI coding points was selected based on the introduction of several commonly point centroid localization algorithms of GSI coding points.At the same time,the gray factor distribution and signal-to-noise ratio (SNR) of GSI coding point were analyzed.And the method of optimizing the exposure time to reduce the GSI coding point visual measurement error was proposed due to the difference of measurement distance.Finally,it was verified by physical experiment and the error analysis was carried out.The experimental results show that the optimized exposure time has a certain effect on improving the accuracy of GSI coding point visual measurement.