The article mainly describes the development process of AB/EQ56 steel plate for ocean engineering with thickness ≤50mm in Wuyang Iron and Steel Co.,Ltd.(Wugang),and studies the chemical analysis,metallographic structure,tensile strength and serial temperatures impact toughness of the steel plate.The results show that a good match of strength and toughness of AB/EQ56 steel plate with thickness ranging from 12mm to 95mm produced by ultra low alloying component control,controlled rolling and controlled cooling,proper quenching and tempering process,of which the properties are all conforming to the requirements of ABS rules.The steel plate has passed the certification of ABS and is qualified for production.More than 7000 tons of such steel plate have been ordered,which mainly apply for the cantilever beam of offshore oil platform. The article mainly describes the development process of AB / EQ56 steel plate for ocean engineering with thickness ≤50 mm in Wuyang Iron and Steel Co., Ltd. (Wugang), and studies the chemical analysis, metallographic structure, tensile strength and serial temperatures impact toughness of the steel plate. The results show that a good match of strength and toughness of AB / EQ56 steel plate with thickness ranging from 12mm to 95mm produced by ultra low alloying component control, controlled rolling and controlled cooling, proper quenching and tempering process, of which the properties are all conforming to the requirements of ABS rules. the steel plate has passed the certification of ABS and is qualified for production. More than 7000 tons of such steel plates have been ordered, which mainly apply for the cantilever beam of offshore oil platform.