The preparation of glasses from gels in the ternary system of SiO2-ZrO2-B2O3 has been investigated. The crystallization character of ZrO2 particles and high-temperature structure stability in the SiO2-ZrO2-B2O3 gels were analyzed. The effect of B2O3 as the inhibitor of crystallization was illustrated. Finally, the result that the purified DD3 single crystal superalloy melt can retain high undercooling in the SiO2-ZrO2-B2O3 coating mold indicates that the coating has an ideal non-catalytic nucleation property.