Abstract: Objiective : Analysis the value of the chemotherapy before operation to the gigan-tic thymic maliglnt tumor. Methods : to compare the results of operation between chemotherapy and no chemotherapy group with retrospectively and prospectively Results : the group of reduction chemotherapy has a high rate of resection, low volume of bleeding, the disappear of the obstruc-tive syndrome of superior vena cava, low mortality after operation. the high level of the survival rates for 1/3 5 years of reduction chemotherapy group compared with that of no reduction chemotherapy. Conclusions : we should give a reduction chemotherapy if we can't performed a radical resection estimate with CT and clinic syndrome such as the obstructive syndrome of supe-rior vena cava. that is included: 1. the obstructive syndrome of superior cavity vein. that is in-cluded. 2 CT scan: gigantic tumor located in all the period of anterior mediastinal, the disappear of the surface of the huge blood vessel. 3 the growth of tumor towards double pleural, the phrenic nerve will be injured probably. 4 company with thoraxfluid.