Abstract: As there is deformation perturbation in the laser welding process of 3D joint seam,the real-time measurement and dynamic compensation in the welding process is used to track accurately a 3D trajectory.The real-time measuring of the 3D joint seam welding is achieved with a laser visual sensor on a five-axis NC welding machine tool,the bias information of tracking joint seam is transformed from measuring coordinate system to workpiece coordinate system,the feed amount of axes is compensated real time,and the dynamic compensation in the welding process of 3D joint seam is realized.The stability of the loop-closed control system with 3D joint seam measuring feedback is analyzed,and the proposed arithmetic is testified by experiment,which indicates that the real-time measuring and dynamic compensation in the 3D joint seam welding process satisfies the track control requirement in 3D laser welding.