The invention discloses a sealing material used for groove-outside plating of an engine cylinder block, wherein the sealing material is of a syrup material. During use of the sealing material, at least one axial end face of a workpiece is coated with the syrup material, the workpiece is axially pressed out through a workpiece frame, and the axial end face of the cylinder block is sealed through the syrup material with viscosity capable of meeting the sealing effect. During plating, good sealing effect is achieved, and normal operation of the plating process is guaranteed; meanwhile, easiness in cleaning after plating is achieved, and working efficiency is improved; during plating and in the late period, environmental protection of surroundings is favorably guaranteed, and problems that materials of sealing gum and the like cause environment pollution, reduction of working efficiency and affection of plating quality are solved.