Abstract: As the composition of 11MnNiCrMoV steel plate has gone through four stages of evolution,the content and equivalent of carbon in the steel are gradually reduced and the weldability of the steel plate is improvel which lay a foundation for reducing or eliminating welding pre-heating．With above development combining rising bake temperature of a matching electrode for11MnNiCrMoV steel plate to reduce the content of diffusible hydrogen,unprehaet welding of the steel plate can be performed．