To solve the problem of the traditional flexible measuring system due to the imperfect robot module and the changing parameters, a calibration technology of high-precision flexible coordinate measurement system is proposed. Binocular stereo vision method is employed to construct the global measurement unit. In order to ensure the accuracy, a camera calibration method which is based on space grid control field, and a method of the global space precise positioning are proposed. The pose transformation of the robot in space can be accurately measured by the two global cameras in the scene, through measuring the controlling points on the stereovision sensor. The experimental results verify that the error of the global camera is less than ±0.1 mm, and the error of the whole measurement system is smaller than ±0.15 mm. The measurement can satisfy the precision requirement of the system.