Abstract: Water leakage occurred in a SA-192 high-frequency welded finned tube. The cause of water leakage was analyzed by macroscopic observation, size measurement, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis, hardness test and other methods. The results show that the main reason for water leakage was that the high frequency current was concentrated on the surface of the steel pipe during welding, and the input power was large and the welding rate was small, resulting in serious local heating on the surface and overburning defects. The overburning defects led to the accumulation of a large amount of welding slag on the surface of the steel pipe, which reduced the plasticity and toughness of the matrix material and promoted the formation of surface pits and holes.