The invention discloses a method for rapidly forming a microwave curing water-soluble core and belongs to the technical field of casting. The method disclosed by the invention comprises the followingsteps: S100, preparing a spraying solution; S200, performing droplet jetting forming; S300, performing intermittent microwave curing; S400, wetting or spraying an inorganic solution; S500, performingsecondary intermittent microwave curing; and S600, sintering. According to the method disclosed by the invention, the core is subjected to microwave hardening pre-forming and then subjected to inorganic salt solution impregnation, secondary microwave curing and sintering; and since the wetting property of the inorganic salt solution is extremely high, pores filled with the pre-formed core can be fully wetted, the inorganic salt is separated out by crystallization in the secondary intermittent microwave curing process, and the strength of the core is obviously improved.