The invention discloses a tail dragging gas protecting cover for welding. The tail dragging gas protecting cover for welding comprises a protecting cover shell and a ventilation pipe located in the protecting cover shell; the protecting cover shell is provided with a first side face, a second side face, a third side face, a first end face and a second end face, and the first end face and the second end face are located at the two ends of the protecting cover; the first side face and the second side face correspond to a first welding material and a second welding material on the two sides of a weld joint correspondingly; the included angle between the first side face and the second side face is larger than or equal to the included angle between the first welding material and the second welding material on the two sides of the weld joint; the two ends of the ventilation pipe are connected with the first end face and the second end face in a fastened manner correspondingly; the pipe wall, the first side face and/or the second side face of the ventilation pipe are provided with exhaust holes; and the third side face is provided with a welding gun gripper, a first control mechanism controlling the distance between a welding gun and the protecting cover, and a second control mechanism controlling the height of the protecting cover.