To produce the metal die of an automobile deck part of high quality at low cost with a short cycle, a new method of manufacturing the die, based on rapid prototyping and rapid tooling, is proposed in tbis paper. First, the technological process of rapid processing (RP) technology and the large scale rapid processing and manfacture (RP&M) eqdipment SSM 1600 that is based on the innovative idea of concunent processing in a divided field are introducedi The SSM 1600 eqdipment supplies a gap in the field of making large prototypes. The technology of the unbaked ceramic mold casting process based on RP technology is also introducedi The method of 3D non linear coupled thermo mechanical FEM analysis is adopted to analyze the dimensional accuracy of the die of an automobile deck part during the casting solidification process. The simolation result can be used to modify the CAD modal to furtber improve the precision of the die. The system of manufacturing the die of an automobile deck part based on rapid prototyping has gained success by the verification of practical production.