The invention discloses a preparation method of blue gradient glaze sanitary ceramic. A glaze material is prepared from basic glaze, silicon dioxide, dolomite, zinc oxide, zirconium silicate, feldsparpowder for glaze, vanadium-zirconium blue and the like; glaze slurry A and glaze slurry B, which have different vanadium-zirconium blue content, are prepared through the glaze material; the glaze slurry A and the glaze slurry B are sprayed on the surface of a sanitary ceramic white body in sequence, wherein the spraying amount of the glaze slurry A is gradually reduced from the top to the bottomof a white body spraying region and the spraying amount of the glaze slurry B is gradually increased from the top to the bottom of the white body spraying region; then the glazed white body is fired in a tunnel kiln at 1202 DEG C to 1250 DEG C for 15h to 18h to obtain a blue gradient glaze sanitary ceramic product. The obtained product meets the processing and utilization performance requirementsof the sanitary ceramic, has a good gradient effect and an extremely good decoration effect, and meets the requirements of individualized bathrooms.