The objective of the invention is to provide waterborne ceramic digital spray-painting ink and a preparing method thereof to overcome defects of present waterborne ceramic digital spray-painting ink. To achieve the objective, the provided ink is prepared by mixing water, glycerol, propylene glycol, glycol, polyethylene glycol, n-butanol, a dispersant, a coupling agent, a surfactant, a defoamer, an anti-settling agent, a sterilizing agent and pigment. The water, the glycerol, the propylene glycol, the glycol, the polyethylene glycol, the n-butanol, the dispersant, the coupling agent, the surfactant, the defoamer, the anti-settling agent, the sterilizing agent and the pigment are fully mixed according to a ratio, the mixture is ground by a sand mill for 5 h at a speed of 2000 r/min until the granularity is about 150-350 nm, viscosity and surface tension of the product are tested, and the ink is obtained when the viscosity and surface tension are qualified.