The head of accumulator is fabricated by pressed petal by manual arc welding, due to improper operation of the operator, large defects such as slag and blowhole are found during RT inspection after welding, which need to be repaired.The head of accumulator is spliced with melon petal and spherical shape and welding position is upward climbing welding,and the material is austenitic stainless steel. Defects can’t be removed by carbon arc air gouging, but can only be removed by grinding wheel.Because the shape of the grinding parts and operation in the repair welding process are not paid attention to during the defect grinding process, cracks are found by RT after repair welding. In this paper, the chemical composition of accumulator material, grinding shape of defect parts, welding technology, welder operation and other aspects are analyzed. And finds out the cause of cracks on the basis of analysis, puts forwards measures to control cracks,（1） After the defect is removed, the transition should be smooth and there should be no sharp grooves;（2） The swing width of welding rod is not easy to be too large. Use tooling to change upward climbing welding to horizontal welding position;（3） Strengthen technical control capacity. Provide production experience for the repair of accumulator head in subsequent projects.