The invention relates to the field of epoxy resin preparation, in particular to a toughened epoxy resin system for a bicycle structure and a preparation method of the toughened epoxy resin system. The toughened epoxy resin system is prepared from the following raw materials in parts by weight: 50-60 parts of E-51 epoxy resin, 8-12 parts of E-03 epoxy resin, 10-15 parts of novolac epoxy resin, 10-15 parts of polyhydroxy thermoplastic elastomer, 5-7 parts of imidazole latent curing agents and 1.5-2 parts of organic urea-based accelerators. The preparation method is simple, easy to operate, high in scientific property and suitable for industrial production, and realizes the purpose of toughening the epoxy resin system; besides, the good technological processing properties of moderate viscosity and long application period are realized, and the cured epoxy resin has quite good mechanical performance.