Abstract: Aiming at the coaxiality error detection and adjustment between lathe tailstock hole and spindle in the field environment, a rapid and high-precision detection of coaxiality error based on laser alignment and photoelectric detection is proposed and a measurement system with PSD sensor and collimated beam as the core is designed. By driving the laser collimation module and the photoelectric probe to rotate, the collimated beam forms the track information in the PSD and the improved ellipse fitting algorithm based on RANSAC is used to fit the coordinates of centre point of the trajectory. By driving the tailstock sleeve to move along the axial direction, the coordinates of the centre points of multiple sections are obtained which are used to fit the axis. Finally, the coaxiality error of the tailstock hole relative to the spindle is calculated according to the minimum containment area criterion for the coaxiality error evaluation. The uncertainty of the measurement system is up to 0.003 2 mm and the error range of the measurement experiment at the same position is less than 0.01 mm., which can meet the coaxiality measurement requirements of lathe tailstock adjustment.