The effect of nano-Yb2O3 on the crystallization mechanism and kinetics of fused quartz were studied. The effect of nano-Yb2O3 on crystallization ratio of fused quartz ceramics was studied by means of XRD, and the effect of nano-Yb2O3 on the crystallization mechanism of fused quartz ceramics was studied by kinetic method, meanwhile, the isothermal crystallization kinetics of two kinds of fused quartz ceramics were discussed. The results show that the grain growth mode of fused quartz ceramics is two-dimensional growth accompanied by one-dimensional and three-dimensional growth, while the grain growth mode of fused quartz ceramics with nano-Yb2O3 is two-dimensional accompanied by three-dimensional growth. The activation energy E of samples B and samples Y are 874 kJ/mol and 1 188 kJ/mol, respectively. With the introduction of nano-Yb2O3 in fused quartz ceramics, the "active nucleation point" of SiO2 glass for cristobalite reduce greatly, the stability of the glass surface structure increases, the crystallization activation energy increases, and the crystallization ratio of fused quartz reduces greatly.