The invention provides a culture system which contains defined components and efficiently acquires induced pluripotent stem cells (iPS cells) from somatic cells. The culture medium additive provided by the invention contains vitamin C, vitamin B12, insulin, glycogen synthase kinase-3 inhibitor, receptor tyrosine kinase and antioxidant. The culture medium additive provided by the invention can also contain a substituted serum cell growth promoter. The invention also provides a complete medium acquired by inducing pluripotent stem cells, which is prepared from one or more of basic culture medium, serum and substituted serum additive and the culture medium additive. The culture system provided by the invention does not have serum, has no animal source pollution, contains defined chemical components, efficiently acquires iPS cells, can maintain cell growth and proliferation in the process of conversion from somatic cells to iPS cells under the condition that feeder cells do not exist, simultaneously accelerates the induction course of the iPS cells obviously, and greatly improves the efficiency of inducing the somatic cells into the iPS cells.