The invention relates to a manufacturing method of an underglaze white double crystal fancy glaze. The method comprises the steps of preparing materials according to a formula, manufacturing a frit, sieving by using a ball mill and modulating, wherein the frit is made from borax, potash feldspar and quartz; a ground glaze is made from potash feldspar, zinc oxide, calcite, quartz and frit; and an overglaze is made from frit, barium carbonate, iron red, potash feldspar, titanium oxide, zinc oxide, bentonite, quartz, iron oxide red and zirconium silicate; dry grinding frit materials, burning the frit materials at 1250 DEG C, and cooling fast to obtain the frit; sieving ground glaze and overglaze materials by using the ball mill; wet ball milling, and sieving by using a 250 mesh sieve; modulating the ground glaze and the overglaze: mixing the crushed frit respectively with the ground glaze and overglaze materials which are sieved and wet ball milling mixtures so as to modulate the mixtures into slurries at 45-50 baume degree; burning: spraying glaze on a green body, wherein the thickness of the ground glaze is 0.4-0.7mm, the thickness of the overglaze is 0.3 mm, and feeding the green body into a roller way to be burnt into the underglaze white double crystal fancy glaze in an oxidizing atmosphere; after burning, natural, smooth and crystal clear decorative patterns can be generated.