In order to resolve the problem that Laser Tracker System(LTS) can not continuously measure Corner Cube Retro-reflector(CCR) position in dynamic conditions for CCR's receivable angle is restricted,an angular automatic calibration mechanism for LTS is designed to measure the CCR positions in real time.The calibration mechanism mainly is consists of a precision circular guide-way and a angular automatic adjustment device,which can make the CCR track the laser beam emitted from LTS all the time.The designed calibration mechanism and Hexagon Globle9128 coordinate measuring machine are used to compensate the angular measuring error of LTS.The experimental results demonstrate that the maximum angular measuring error of LTS in measuring distance of 0.752 m is decreased sharply from 34.69 μm to 9.71 μm in horizontal direction and from 35.43 μm to 10.03 μm in vertical direction,which shows the LTS angular measuring accuracy is effectively improved.