Abstract: Aiming at the problems of shaft diameter measurement method in accuracy, reliability and adaptability, a precision and on-line measurement method of shaft diameter based on 2D laser measurement and full range calibration is proposed. In this method, 2D coordinate data of the inspection section is collected synchronously using the 2D laser profile sensor, and the radius of the measured shaft is solved based on the collected coordinate data and the least squares fitting algorithm. The test profile is optimized and determined based on the principle of minimum area. The full range calibration method is used to establish the error model of shaft diameter measurement, and the error compensation algorithm is used to compensate the nonlinear error of the system in real time to improve the measurement accuracy of shaft diameter. The research results show that the relative error of the method is less than 1%, and the non-contact, on-line and high-precision measurement of shaft diameter is achieved without disassembly.