The invention discloses a surface modification method of hollow glass beads. The method comprises the following steps: firstly, removing surface impurities of the hollow glass beads with absolute ethanol or acetone, and then drying the hollow glass beads for 3 to 5 hours; secondly, adding the dried hollow glass beads into an agitator to be continuously heated after the agitator is preheated, and adding a coupling reagent 0.2-1.5% of the mass of the glass beads after the surface temperature of the hollow glass beads is increased to 95 to 135 DEG C; and thirdly, continuously stirring the hollow glass beads for 10-30min at 95 to 135 DEG C, and then discharging the hollow glass beads to obtain the hollow glass beads with modified surfaces. According to the method, the agitator is adopted to perform dry modification, the technology is simple, the operation is easy, the modification time is short, the cost is low, subsequent drying is not required, and the energy consumption is reduced. The hollow glass beads treated through the method can be better dispersed in epoxy resin, the binding property between the resin and fillers is improved, the material strength is improved, and the mechanical property of the composite material is obviously improved.