The invention discloses a double-layer motor main pole coil welding method and a clamp used in the method. The method includes the steps of firstly, aligning an inner frame of a first layer coil and an inner frame of a second layer coil to form an integrated motor main pole coil, supporting and positioning the aligned motor main pole coil, and abutting the side face of an inner connector of the first layer coil and the side face of an inner connector of the second layer coil; secondly, arranging a medium-frequency induction heating device, and heating the abutting position of the inner connector of the first layer coil and the inner connector of the second layer coil through the medium-frequency induction heating device; thirdly, placing a brazing material at the abutting position after heating for a period of time, and brazing the inner connector of the first layer coil and the inner connector of the second layer coil together after the brazing material is melted. By means of the method, the inner connectors of the two layers of coils can be well welded, the damage of overheated copper to an insulating material is reduced, standard brazing operation is easy, the requirements for operators are low, and product quality is stable.