A real-time robotic weld tracking system based on laser vision sensor is designed for intersecting seam. Firstly, the traditional image processing method is used to determine the weld feature point in the first frame when there has no arc noise. Then, an extending and adopting Kalman Filter with Spatio-Temporal Context algorithm was proposed to extract the weld feature point when the laser stripe was blocked by heavy arc and splash noise during welding. Next, in order to control torch to weld automatically, the torch frame was established through novel three points principle and an expanding circle and arc length method. In addition, a segmentation weld method and an intermediate proportional interpolation method for step-size control of mobile torch were proposed to guarantee the accurate of weld. Finally, Experiments and analyses results show that the tracking system is good in real-time, accuracy, stability and flexible, which can meet the weld requirements.