Abstract: The ductile-brittle transition temperature,chemical composition,microstructure and fracture of welded metal are investigated to discuss the difference of impact absorbed energy between butt weld and deposited metal.The results indicate that the ductile-brittle transition behavior of the butt weld metal is different from that of the deposited metal,and the impact absorbed energy of the butt weld metal is lower than that of deposited metal under the same temperature.The increase of carbon content and the decrease of manganese content make the ductile-brittle transition temperature of butt weld metal increase.The difference of welding bead distribution between butt welding and deposition welding will cause the content of troostitic structure in butt weld metal higher than that of deposited metal,and the crack in butt weld metal is formed easily.The crack stability extend distance of the butt weld metal is shorter than that of the deposited metal.