The invention discloses lead-free superfine glass powder and a synthetic method thereof. The lead-free superfine glass powder comprises the following components in percentage by weight: 35-55% of Bi2O3, 5-30% of SiO2, 5-25% of B2O3, 2-10% of ZnO and 1-5% of Al2O3 and is synthesized by respectively taking bismuth nitrate, ethyl orthosilicate, boracic acid, zinc acetate or zinc nitrate and aluminum isopropoxide or aluminum nitrate as the precursors of Bi2O3, SiO2, B2O3, ZnO and Al2O3, respectively taking deionized water, anhydrous ethanol, citric acid and nitric acid as a solvent, a complexing agent and a catalyst and adopting a sol-gel method. The lead-free superfine glass powder disclosed by the invention has the advantages of no lead, environment friendliness, high chemical stability, small powder particle size and high sintering activity, can be used as the inorganic binder of various ceramics and glass substrates and also be used as an inorganic binder phase and added to electronic paste, is easy to improve the printing and sintering property of the electronic paste through a screen mesh due to small particle size and has a wide application prospect in the fields of electronics and electrical appliances.