The purpose was to help designers understand the cushioning design methods based on cushioning coefficient-maximum stress curve. The cushioning coefficient-maximum stress curve was equivalent to an infinitive equation. The infinitive equation was composed to infinitive equation group together with the cushioning pad area and thickness formula. By this means, the cushioning pad design methods based on cushioning coefficient-maximum stress curve was converted to the problem of solving infinitive equation group. By this method, the classic cushioning pad area and thickness calculation methods were analyzed and classified. It was concluded that the essence of the classic cushioning design methods is adding a restriction to the infinitive equation group and converting the original infinitive equation group to posed equations.