This paper presents a new line-based calibration method for automatically computing the transformation relationship between industrial robots and workcell. The calibration method mainly depends on the position-sensitive detector (PSD) servo control of the robots. The developed servo controller allows precisely positioning the laser beam (line) from a single laser pointer attached at the end-effector of robot onto the center of the PSD in a well-designed lateral-effect PSDs fixture. The selected PSD in the fixture has high performance with the resolution of 0.5 mum. Once the precision localizations/positioning in the centers of multiple PSDs are achieved, the group of points in the robot base frame and workcell frame can be generated by using the intersection of laser beams (lines) and by using the predefined fixture-workcell information, respectively. A quaternion algorithm and the least square method are then employed to determine the transformation relationship between robot base frame and workcell frame. The experiments have been implemented on an ABB industrial robot IRB1600, the results verify the effectiveness of both the PSD servoing and the line-based calibration method as well as demonstrate the performance of the whole system.