Molecular pump with magnetic suspension is an important vacuum extractor. The machining accuracy of turbine-rotor has crucial influence on the key parameters of molecular pump, such as pumping speed, compression ratio. A clamping accuracy detection and display system of semi-fished turbine-rotor was established. The maximum coaxiality error and its position could be detected, displayed and recorded easily. With a precision fine tuning device, coaxiality error could be reduced from 30µm to 10µm. This system effectively reduces the turbine-rotor’s centrifugal force, and increases the stability of molecular pump with magnetic suspension.