Abstract: Detection and measuring technology is one of the main techniques in modern manufacturing industry, and it is also the key measure to ensure product quality.The precision of a workpiece will be improved when CCD sensors are used to enlarge the image of the projection of the workpiece diameter, display in real time, and feedback to the CNC system and give the compensation for the cutting tool.In this paper, based on the line array CCD measurement system for CNC lathes, the authors analyzed the measurement errors of the line array CCD measurement system used in CNC lathes, and proposed the measures to reduce the measurement errors of the line array CCD measurement system.