In robot visual guidance, the laser line projection position often has a certain deviation from the position of the torch head, resulting in low real-time correction accuracy in the case of variable weld shape. Therefore, a correction method based on Smith predictive control model was proposed. Firstly, the center point of the weld was extracted by using the skeleton and rectangular opening operations in morphology as the core algorithm. Then, the amount of correction was calculated according to the center point of the weld, and the amount of correction was stored in the container in order.Moreover, the mathematical model constructed by Smith principle was used to process the stored data. Finally, the processed data was employed to perform lag correction point by point. The results of data simulation and actual test show that the actual correction accuracy is less than 0.35 mm, which meets the requirements of correction accuracy in engineering welding with strong practicability.