The present invention relates to a pharmaceutical composition for the treatment and prevention of cancer and the preparation method thereof, especially to a cell differentiation agent named CDA-II which is prepared by reverse phase chromatography of fresh human urine. The pharmaceutical composition is effective for the treatment and prevention of cancer. The active components in CDA-II contain differentiation inducers, differentiation helper inducers and an anticachexia agent, which act cooperatively to achieve the best therapeutic effect.