Abstract: For the actual situation of the crack in weld produced between the shell and steel containment gate insert plate in the a domestic nuclear power engineering project, the quality control of welding process, welding hot crack, cold crack, lamellar tearing, the causes of stress corrosion crack and reheat crack were analyzed in detail. The SA738Gr. B steel weld cracking reasons were found and the reasonable precautions were taken to avoid cracks, which provides references for subsequent project SA738Gr. B steel welding process.