The invention relates to a dustproof structure unit for an electric welding machine. The dustproof structure unit comprises a radiator, wherein the radiator is installed in a housing of the welding machine, and an installing surface used for installing an IGBT (Insulated Gate Bipolar Translator) module circuit unit is formed on the radiator. The dustproof structure unit is characterized in that a left bracket and a right bracket are respectively installed on the left and right sides of the installing surface of the IGBT module circuit unit, an upper wind board and a lower wind board are respectively installed on the upper and lower ends of the installing surface of the IGBT module circuit unit, a closed cavity is formed by the upper wind board, the lower wind board, the left bracket, the right bracket, the radiator and the housing of the welding machine, the left bracket and the right bracket are fixed together with the radiator through first bolts, and the upper wind board and the lower wind board are fixed together with the radiator through third bolts which are arranged in waist-shaped holes. According to the dustproof structure unit, the IGBT module circuit unit in the electric welding machine can be protected, and the working performance of the electric welding machine can be improved.