The invention discloses a preparation method of light curing molding potassium-sodium niobate leadless piezoelectric ceramics. The method comprises the following steps that potassium-sodium niobate leadless piezoelectric ceramic powder is modified, and finally activated piezoelectric ceramic fine powder with the excellent performance is obtained; then, the activated ceramic fine powder is mixed with a photo initiator, acrylic resin, a dispersing agent and a defoaming agent through ball milling, and vacuumizing is performed to obtain uniform-dispersed leadless piezoelectric ceramic slurry withproper viscosity and high photo-curing activity; then, the prepared ceramic slurry is subjected to photo-curing molding through a 3D printer, and a ceramic green body is obtained; finally, the ceramicgreen body is subjected to two-step degreasing, sintering, silver coating and polarization to obtain dense flawless potassium-sodium niobate leadless piezoelectric ceramics. The obtained ceramic slurry is uniform in granule dispersion, high in illumination activity, low in viscosity and capable of printing complex components of any shape in the photo-curing process, the sintered sample is high indensity and excellent in electric performance, and the using requirement of a piezoelectric device is met.