Abstract: Coupling alignment of the motor-driven centrifugal compressor unit will affect the operation stability of the unit. Therefore, it is necessary to verify and correct the cold alignment data of the compressor manufacturer on site to ensure the accuracy of cold alignment, thus improving the quality of cold alignment of the unit. According to the structure and operation characteristics of centrifugal compressor unit, the differences of the unit in cold state and normal operation state were analyzed, the factors affecting the cold alignment were obtained, and the formula for calculating and correcting the cold alignment data was proposed. The effect of cold alignment was analyzed from the four aspects of material thermal expansion, rising height of shaft and deflection of alignment tool. In the calculation process of thermal expansion values, an obvious linear relationship was found, which simplified the numerical calculation of thermal expansion. The rising height of the rotor shaft center was obtained from the condition monitoring tool, the jacking height of rotor in the process of cold alignment was corrected, and the corrected cold alignment data was obtained finally, which is of reference significance to guide the cold alignment of compressor.