The invention belongs to the technical field of solid waste comprehensive utilization, and particularly relates to a preparation method of a glass-fiber-reinforced epoxy resin composite material modified by circuit board recovered powder and nanoparticles. The preparation method provided by the invention comprises the following steps of: modifying glass fibers with a coupling agent to obtain surface-activated glass fiber reinforcement; carrying out surface activating treatment on dry circuit board recovered powder and nanoparticles, and then mixing with epoxy resins to obtain an epoxy resin base body filled and modified by the circuit board recovered powder and nanoparticles; and finally compounding the coupling-agent-modified glass fiber reinforcement and the epoxy resin base body filledand modified by the circuit board recovered powder and nanoparticles to obtain the glass-fiber-reinforced epoxy resin composite material modified by circuit board recovered powder and nanoparticles. The preparation method utilizes the coupling-agent-treated glass fibers to improve the interfacial bonding properties between the glass fibers and the resin base body and to improve the interfacial bond strength of the composite material, utilizes the strength and toughness of the glass fibers to strengthen and toughen the resin base body, and utilizes the surface-activated recovered powder and nanoparticles to fill and modify the resin base body, thus improving the overall performance of the composite material and significantly improving the interfacial bond strength of the composite materialand the mechanical properties of the glass fiber composite material, and can be widely applied in the fields of aerospace, automobile shipping, traffic transportation, mechatronics, etc.