The invention provides a method of treating liver cancer comprising administering anti-DKK1 monoclonal antibody to a subject in need thereof. Anti-DKK1 monoclonal antibody can also be administered for preventing or ameliorating cancer metastasis and for neutralizing serum and tissue DKK1 in liver cancer patients. The use of anti-DKK1 monoclonal antibodies is based on the discovery of the upregulation of DKK1 in human liver cancer.