The invention discloses an evanescent die process. The evanescent die process is characterized by comprising the following steps of: selecting foaming plastic beads, manufacturing a model; enabling the beads to expand to be in a certain size through hot water pre-frothing, steam pre-frothing and vacuum pre-frothing, curing and frothing forming; clustering model composition, coating a model; vibrating and shaping; pouring and displacing; and cooling and cleaning, wherein the full mold casting ramoff is simple, a casting piece can be hoisted out when a sand box is inclined or can be directed hoisted out form the sand box, the casting piece and dried sand are naturally separated, and the separated dried sand is reused after treatment. According to the process, a die is not required to be taken out, and a parting plane and a sand core are not required, and thus the casting piece has no flash, no burrs and no pattern tapers, and the dimension error caused by core combination is reduced; and compared with the conventional sand casting method, for the evanescent die process, the 40%-50% machining time is reduced.