The utility model discloses a condensation heat exchanger welding spot protective structure. The welding spot protective structure is characterized in that fume isolating cavities are formed around welding spots of a heat exchanger water pipe and completely encircle the welding spots, and shells of the fume isolating cavities do not make contact with the welding spots. Each fume isolating cavity is formed by an isolating baffle and a condensation heat exchanger shell in a defined mode, and the isolating baffles and a heat exchange water pipe are fixed through welding. In this way, in the actual working process, high-temperature and high-humidity fume in a condensation heat exchanger does not make direct contact with the welding spots and only makes contact with welding seams between the isolating baffles and the stainless steel heat exchange pipe; as the welding seams do not bear pressure, the corrosion resistance of the welding seams is good, corrosion to the welding spots is effectively avoided, and the service life of the welding spots is prolonged.