Abstract: Disclosed herein is a culture system for chemical induction of pluripotent stem cells, comprising a basic culture medium and a composition for performing chemical induction of reprogramming process. The said composition comprises a thymine analogue, a cAMP activator, a TGF-? receptor inhibitor, a bone morphogenetic protein, a RA receptor activator, a GSK3 inhibitor and a basic fibroblast growth factor. And the said culture system is free of serum. By using the culture system as described herein, there is no need to frequently replate cells during culture, such that culturing process is simplified and loss of cells resulting from replating cells is reduced. As the culture system is free of serum, subsequent collection of pluripotent stem cells and molecular mechanism analysis are simplified, thereby facilitating establishment of no animal origin culture systems for induction of pluripotent stem cells.