A resin composition is provided, which includes an oligomer formed by reacting bisphenol epoxy resin monomer, aliphatic diglycidyl ether, anhydride compound, and catalyst, wherein the molar ratio of epoxy groups of the bisphenol epoxy resin monomer and aliphatic diglycidyl ether to anhydride groups of the anhydride compound is between 3.5:1 and 8.8:1. The bisphenol epoxy resin monomer and aliphatic diglycidyl ether have a molar ratio of 0.3:1 to 1.3:1, and the viscosity of the resin composition is 20 Pa·s to 80 Pa·s at 25° C.