The invention relates to the technical field of calcium gluconate crystallization, particularly to an apparatus and a method for flash vaporization continuous crystallization of calcium gluconate, andapplications of the method and the apparatus. The apparatus comprises a first dissolving tank, an oxidation reaction tank, a plate-and-frame filter press, a first-stage nano-filtration membrane concentration device, a second dissolving tank, a heating chamber, a single-effect vacuum cooling flash vaporization crystallization device, a slurry groove, a centrifugal machine, a granulator and an internal heating fluidized bed drying device. The method comprises: dissolving and volume metering, enzyme oxidation, enzyme deactivation and filtration, concentrating, dissolving and decolorizing, circulating filtration, finished product crystallization, centrifugal washing, and granulating drying. According to the present invention, the apparatus has advantages of high energy utilization rate, smalloccupation area, low investment cost, high labor productivity, automatic control, uniform crystallization granularity, adjustability within a certain range, no scaling, no scabbing, and long-term continuous production.