This model utility relates to a resistance spot welding head which is characterized in that the contact surface between an electrode head for connecting the air cylinder and a steel plate to be welded is designed into a rectangle; an anti-rotation rod is sleeved on the periphery of the air cylinder to prevent the air cylinder to be form being moved during the working process. The utility model has the advantages that since the fixed electrode head is changed into a rectangular copper square block, the steel plate to be welded is closely fitted with the fixed electrode head, the problems of sunken soldered points and distortion can be overcome, and the quality of the welded appearance is greatly improved; more importantly, the rectangle surface designed in the position as well as the surface of the cylindrical electrode head is greatly increased, and the quality accidents caused by long-term use of the electrode head are eliminated such as false welding, unsoldering, soldered point concavity, distortion, and the like; and the problems of false welding, unsoldering, soldered point concavity and distortion which are caused since the electrode head is not aligned are avoided.