The clinical trial is to evaluate the efficacy of single autologous hematopoietic stem cell transplantation with standard conditioning of melphalan 200 mg/m2 followed by thalidomide maintenance in patients with newly-diagnosed myeloma after receiving 4-6 cycles of induction chemotherapy consisting of vincristin,adriamycin and dexamethasone (VAD) or thalidomide/dexamethasone between 18 to 65 years.