The invention discloses a longitudinal seam welding special machine with a linear structure light type vision sensor and a control method thereof. The longitudinal suture welding special machine comprises a welding gun, the linear structure light type vision sensor, an industrial control computer and an execution mechanism, wherein the welding gun is fixed on the execution mechanism; the welding gun and the linear structure light type vision sensor are connected to an operation rail of the longitudinal seam welding special machine, and the linear structure light type vision sensor is arranged in front of the welding gun; and the output end of the linear structure light type vision sensor is connected with the execution structure through the industrial control computer. With the control method, the concept of a coordinate system is established, and a welding seam track is detected through the vision sensor to essentially change an application way of corresponding the welding gun to an image reference point through a rigid body relation, and the method can also be used for tracking the space curve welding seam without limitation of tracking the linear welding track. The longitudinal seam welding special machine detects the whole welding seam track, even if the sensor is out of the visual field, the last section of the welding seam can also ensure the tracking of the whole welding seam.