A machine part measurement system for freeform surface based on laser triangulation was proposed to solve the problems that the offline measuring equipment used for super slender spiral surface workpiece profile error can not meet the requirements of the length and steady rotation of the workpiece. This system was realized by using machine tool to locate, clamp and support the workpiece, the laser detecting system and moving parts to the related motion and control mechanism. The onmachine laser detection hardware technology platform which can make the analysis and treatment to the collected point cloud data and draw the section profile of the measure workpiece was structured. The results show that this system which realizes the accurate measurement of the spiral surface profile does not only improve the efficiency and the accuracy of the measurement, but also the precision of the slender spiral surface workpiece.