Abstract: Synthetic beacon technique provides beacon signal for adaptive optical system, which is used to correct the wavefront aberration caused by atmospheric turbulence successfully in astronomical observation and laser transmission. However, anisoplanatic errors is one of some insuperable difficulties. Many academic research works were studied but there were few reports for experiment measurement all over the world. In this paper, the measurement method of anisoplanatic errors was proposed, and the high precision measurement system was independently designed, which concluded two Hartmann wavefront sensors using high sensitive EMCCD detectors to get the wavefront of Rayleigh beacon and the natural star simultaneity. Two basic experiments were finished, one was focal anisoplanatism errors measurement experiment at the altitude from 8 to 18 km of Rayleigh beacon, another measurement experiment is at the Rayleigh altitude of 12 km with the angle varying from 0 to 100 rad between the synthetic beacon and the natural star. The exact and reasonable measurement result is gained.