The new type of water-cooled mold casting ingot mold system consists of an adjustable ingot mold， a water-cooled copper bottom plate， an insulation cap， and a control system. The size of the water-cooled mold casting is inversely calculated from the size of the material used to produce a thick plate with laminar tear resistance， and a 4-factor 5-level orthogonal test simulation is conducted by using Anycasting software， to determine the optimal ingot mold size under the current water cooling control system （wide surface taper 0.75%， narrow surface taper 0.45%， narrow surface arc radius 1 500 mm， insulation cap height 500 mm） and follow up the cooling process 2 to 8 h after casting. Use the method of adding a separator to the center of the water cooling mold casting to divide the ingot into two parts to achieve one mold double ingots， similar to the directional solidification method， to make the center segregation and loose defects exist on the surface of the billet， making it easier to clean and improve the quality of the billet， And it can make the penetration effect more effective during the rolling process， so as to achieve the purpose of producing laminated tear resistant extra thick plates.200-400 mm plate produced by the said method， internal quality meets the standard JB / T 4730.5-2005 class I and plate with layered tear resistance Z35 performance.