The invention relates to preparation of high-resistivity gas-tightness high-expansion-coefficient aluminum alloy sealing glass powder, wherein the preparation comprises raw material preparing, mixing,heating, drying, water quenching, drying, ball milling and other steps, and the raw materials comprise, by mole, 35-45% of P205, 15-28% of SnO, 15-27% of Bi2O3, 3-7% of ZnO2, 1-3% of SiO2, 2-4% of Na2O, 1-4% of K2O, 2-5% of BaO, and 2-4% of WO3. The application steps comprise: mixing the prepared alloy sealing glass powder and low temperature paraffin slice, heating, stirring, and screening to obtain the glass powder of desired particles; molding with a molding machine, heating, and carrying out thermal insulation to obtain a dewaxed glass billet; and removing oil stain from an aluminum alloyshell, carrying out dehydration, drying, assembling the sealed aluminum alloy shell and the glass billet, placing in a graphite mold, placing in an argon atmosphere furnace, carrying out thermal insulation, and cooling to a room temperature to obtain the electrical connector with advantages of aging resistance, high resistivity and high gas tightness. According to the present invention, the hightemperature oxidation of the metal during the sealing can be avoided, and the late-stage processing difficulty can be reduced.