Abstract: The formation causes of the cladding layer defects in tube plate of the 1 000 MW steam generator were introduced．Based on the cladding layer quality problems occurred in a certain factory，the effect on the seal welding quality of tube to tube plate was analyzed．And the measures were proposed to treat the quality problems，which provide the reference for the treatment of the similar quality problems and improvement of quality in the nickel base alloy cladding layer of tube plate in the future．