The invention relates to an elastic clamping type bent arc plate welding and locating tool. A bent arc plate is formed in a bent mode. The tool comprises a welding part, a lower bending part and an upper bending part from bottom to top. The bending direction of the lower bending part is opposite to that of the upper bending part. The welding part and a transverse plate are arranged horizontally. Face welding is adopted between the welding part and the welding end of the transverse plate. The welding and locating tool comprises a base. A lower electrode is installed in the base in a penetrating mode. An upper electrode is installed above the lower electrode. A welding base located at the side of the lower electrode is installed on the upper surface of the base. The welding base is symmetrically provided with clamping plates. The ends of the two clamping plates are hinged to the welding base through a hinge shaft. The hinge shaft is sleeved with a spring. The spring ensures that the two clamping plates are joined tightly. The clamping plate at one side is provided with an adjusting screw for adjusting a gap between the two clamping plates. The bent arc plate and the transverse plate are installed between the two clamping plates. The inner side face of each clamping plate is provided with an installing cavity for installing the lower bending part of the bent arc plate, a horizontal installing groove for installing the welding part, and a limiting groove for installing a limiting block.