The invention discloses a glass gasket sol, its preparation method, a glass sealing method and a vacuum glass; the glass gasket sol contains Pb single substance or a Pb compound, the preparation method comprises the following steps S1, measuring glass powder with low melting point; S2, configuring a first solvent; S3, configuring a second solvent; S4; configuring a third solvent; S5, mixing the glass powder with low melting point with the first solvent, the second solvent and the third solvent mixture. The vacuum glass comprises a first glass substrate and a second glass substrate; the first glass substrate and the second glass substrate are sealed as one through the glass gasket sol, a vacuum chamber is provided between the first glass substrate and the second glass substrate. The glass sealing method comprises the following steps coating the glass gasket sol along the outer edge of the first glass substrate, and supporting a support, and then pressing through the first glass substrate, drying and vacuum pumping. The glass gasket sol has the advantages of good sol uniformity, good air tightness and high bonding strength.