Shrinkage porosity is one of major defects in castings, which seriously influences the quality of the castings. In general, the common method to eliminate this defect is to increase the liquid feeding ability of the casting through setting a riser in the corresponding position. However, for the casting with large height-to-diameter ratio, narrow and long feeding channel increases the flow resistance of the liquid metal in the late stage of the solidification. It is difficult to achieve a long-range liquid feeding, and the effect of the feeding is very little. Therefore, the penetrated shrinkage porosity in axis is frequently produced in the continuous casting ingots with large height-to-diameter ratio and large cross-section. As the liquid feeding mechanism has no effect on this problem, the solid feeding mechanism is proposed. First, the solid feeding mechanic is clarified by analyzing the effect of the hydrostatic tense stresses on the pore formation and the solid deformation. In addition, the ability of the solid feeding is determined by the value of the fracture of liquids, the content of the gas solute in liquid metal and yield strength of the solid. Then on the basis of this mechanism, reducing the temperature gradient in the radial direction of the casting is proposed to enhance the solid feeding ability. Finally, a verification experiment was conducted, and the results proved the function of the solid feeding on eliminating the shrinkage porosity defects.