The utility model relates to a casting mold, and provides a sand negative-pressure gravity casting mold. The sand negative-pressure gravity casting mold solves technical problems that an existing sand negative-pressure casting sand box is low in recycling efficiency, a vacuumizing system is complex in structure, and reliability is poor. The sand negative-pressure gravity casting mold is applicable to casting large-size hollow conical rotary castings, is high in sand box recycling efficiency and comprises an upper box and a lower box, wherein the lower box consists of a lower sand box, a vacuum pipe and a bottom cover bucket with a vent, the lower sand box comprises a bottom plate, a vacuum pipe extending hole is disposed in the center of the bottom plate, the bottom cover bucket is reversely fastened on the bottom plate, the vacuum pipe consists of a vertical air inlet pipe and a horizontal communicating pipe, a free end of the horizontal air inlet pipe penetrates through the bottom plate to extend in an air suction cavity consisting of the bottom cover bucket and the bottom plate, an air suction opening is disposed on the wall of the vertical air inlet pipe, and a free end of the horizontal communicating pipe is connected with a vacuumizing system. A sand filtering metal net which is extremely easy to be damaged does not need to be arranged on a vacuumizing pipeline to prevent sand from being sucked into a vacuum pipe to damage the vacuumizing system, and accordingly recycling efficiency of the sand box is quite high.