The invention relates to the field of glass and particularly relates to alkali-free silicate glass and a preparation method and application thereof. The alkali-free silicate glass comprises, by mole, 65-75 mol% of SiO2, 11-17 mol% of Al2O3, Ga2O3 and GeO2, 0-8 mol% of B2O3, 0-15 mol% of MgO, 2-10 mol% of CaO, 0.5-14 mol% of SrO and BaO, 0-10 mol% of TiO2, 0.01-2 mol% of Ta2O5 and 0.01-0.5 mol% of Tl2O3. The alkali-free silicate glass has high thermal stability and dimensional stability, a high strain point, a high specific modulus, a low melting temperature, a low liquidus temperature and low density and is suitable for large-scale industrial production.