In order to accurately measure the nozzle throat area of solid rocket motor after test, the on-site measurement of nozzle throat was carried out by using laser tracking technique, and through the tracker to measure the common points. According to the coordinates change of each point to evaluate the uncertainty of the on-site measurement of laser tracker. The experimental results show that using a laser tracker to measure the nozzle throat has great improvement in the measurement of speed, accuracy and convenience as compared with the existing measuring methods. The scheme that use laser tracker to measure solid rocket engine nozzle meets the design requirements of uncertainty measurement. It can promote the measurement of throat neck of solid rocket motor nozzle after trial.