In the shipbuilding industry,the welding efficiency of the ship plate not only has a great effect on the construction cost of the ship,but also affects the construction speed and determines the delivery cycle.The steel plate used for large heat input welding was developed sufficiently.In this paper,the composition of the steel with a small amount of Nb,Ti and large amount of Mn had been designed in micro-alloyed route.The content of C and the carbon equivalent were also designed to a low level.The technology of oxide metallurgy was used during the smelting process of the steel.The rolling technology of TMCP was controlled at a low rolling temperature and ultra-fast cooling technology was used,for the purpose of controlling the transformation of the microstructure.The microstructure of the steel plate was controlled to be the mixed microstructure of low carbon bainite and ferrite.Large amount of oxide particles dispersed in the microstructure of steel,which had a positive effects on the mechanical property and welding performance of the steel.The mechanical property of the steel plate was excellent and the value of longitudinal Akv at-60℃is more than 200 J.The toughness of WM and HAZ were excellent after the steel plate was welded with a large heat input of 100-250 kJ/cm.The steel plate processed by mentioned above can meet the requirement of large heat input welding.