Abstract: The weldability of HG70 steel,including the joint and usage properties,is investigated.Under the condition of restraint welding,the cold crack rate is zerg,showing an excellent joint property.The experimental results of tensile,hardness and impact toughness tests show that in the coarse-crystalline zone the hardness is high,but the toughness is low;in the tempered zone the strength is low,and good coordination between the toughness and strength appears in the fine-crystalline zone.The mierostructure in welded joint consists of martensite,granular bainiteand granular structure.The relationship between the properties and the microstructure is discussed.