According to the special requirement of all glass fiber reinforced resin matrix composite (GFRP) transmission tower head on the fastening strength and insulation performance of connecting parts, GFRP insulated fasteners were developed. A medium-high temperature curing epoxy bulk molding compound (BMC) was designed and developed, and its initial viscosity decreases through blending modification of bisphenol A and bisphenol F epoxy resin. The mechanical properties and water absorption of samples with different ratio of Al(OH)₃, talcum powder, and SiO₂ fillers were tested to determine the material system that meets the requirements of molding process. Non-isothermal DSC measurement was conducted on the optimized material system, and T-β extrapolation and orthogonal tests were applied to evaluate, optimize, and determine the forming process parameters. The results show that the failure load, shear strength, and electrical properties of the product prepared by the optimal material system and forming process parameters meet the design requirements, which indicates this material system is suitable for the manufacture of GFRP fasteners with higher electrical performance.