The invention provides a serum-free culture medium for mesenchymal stem cells. The serum-free culture medium specifically comprises a lipid mixture, glutamine, hydrocortisone, zinc sulfate, sodium butyrate, ferric citrate, vitamin C, recombinant epidermal growth factors, recombinant alkaline fibroblast growth factors, RGD oligopeptides, palmitoyl tripeptide-5, palmitoyl tetrapeptide-7, lithium chloride, L-glutathione, a soybean pancreatin inhibitor, beta-mercaptoethanol, ethanolamine, sodium selenite, Hepes, sodium bicarbonate and a basic culture medium. The serum-free culture medium is free of human and animal resources, clear in chemical component, rich in nutrition, capable of achieving UC-MSCs rapid proliferation, and capable of solving the problem of cells number insufficiency and maintaining the biological features and immunophenotyping stability of the mesenchymal stem cells.