Abstract: An orthogonal test is conducted with the four major process parameters, i.e., the superheat degree of molten steel in the tundish, the water ratio of the second cooling section, the current for electromagnetic stirring(EMS), and the withdrawing speed so as to analyze the central shrinkage and crack as stay with the sectional and sliced samples of the 304L CC round billet under different conditions, and thus to determine the optimal combination of the CC process parameters.And the causes for occurrence of the central shrinkage and the crack are analyzed from different perspectives.Result of actual piercing operation shows that the CC round billet with highly acceptable shrinkage and crack presents good piercing performance, and that provided that the shrinkage and crack of the sliced sample are both classified as Class 0.5, and for the sectional sample, its shrinkage width is ≤ 7.5 mm, the proportional of the shrinkage length >3 mm to the sectional sample length is ≤ 24.91%, it will be ensured that the CC round billet possesses excellent piercing performance.