The invention discloses a method for vacuum smelting and casting for a Mar-M246 alloy. The method comprises the following steps: (1) processing Mar-M246 alloy bars, and the Mar-M246 alloy comprising the following chemical ingredients in percentage by weight: 0.13-0.17% of C, 8-10% of Cr, 9-11% of Co, 9-11% of W, 2.25-2.75% of Mo, 1.25-1.75% of Ta, 5.25-5.75% of Al, 1.25-1.75% of Ti, 0.01-0.02% of B, 0.03-0.08% of Zr, not greater than 1.0% of Fe, not greater than 0.1% of Cu, not greater than 0.2% of Mn, not greater than 0.015% of S, and balance Ni and inevitable impurities; (2) pressing a wax pattern, and combining the wax pattern with a refractory crucible through bonding wax; (3) smearing the wax pattern combined with the refractory crucible, with a paste, and then dewaxing to produce a formwork; (4) roasting the formwork; and (5) filling the refractory crucible with the Mar-M246 alloy bars, and smelting and casting the Mar-M246 alloy bars.