The 0.8BaTiO3-0.2BiYO3 ceramics with alkali-free glass modified were prepared by conventional solid state method. The effect of the alkalifree glass content on the microstructure and dielectric properties of 0.8BaTiO3-0.2BiYO3 ceramics were studied. The mass percentage of glass was x=0, 0.01, 0.03, 0.05 and 0.07 respectively. The results showed that the sintering temperature was reduced after being alkalifree glass modified and the second phase appeared in XRD mapping. The pseudocubic perovskite structure was remained in main phase. The diffraction peak intensity of the second phase was the weakest at ceramics with 3% of mass fraction of doped glass. The dielectric constant was reduced, the curie peak broadening effect was weakened and the ferroelectric property was enhanced after the ceramic was alkalifree glass modified. When the doped amount of glass was less than 3%, the polarization intensity was increased. The polarization intensity was biggest when the doped amount of glass was 3%.