Abstract: Morphology and microstructure of separated fracture were observed by metallurgical microscope and scanning electron microscopy.The results indicate that the inclusions,the center segregation and the banded structure are the causes of separated fracture on tensile sample of high strength ship plate.Combining with production practices,the forced cooling measures upon casting billet solidification end at secondary cooling zone were put forward,with which columnar grains growth can be slowed down and percentage of equiaxed crystal has been increased,and static pressure and central segregation reduce.Thus,the tension fracture separation of the shipbuilding steel plate was prevented remarkably.