In the repair of tail erosion sealing surface of cylinder of cracking gas compressor in petroleum refining and chemical enterprises. In the past,there were some disadvantages such as poor bonding,easy to crack and undercut,and secondary damage of sealing surface in the methods such as gluing and arc welding. Exploring the composite welding technology of gas brazing and fusion welding. After selecting welding materials,adjusting welding specifications,and using special tools created by ourselves,the welding seam was repaired with high quality,which reduced the difficulty of the operation and improved the repair quality and efficiency.