A method of forming a biomass epoxy resin composition includes mixing 100 parts by weight of biomass 2,5-furandicarboxylic acid, 900 to 1100 parts by weight of epihalohydrin, and a catalyst to form a mixture. The method includes heating the mixture to 80° C. to 95° C. to react for 2 to 5 hours to form a ring-opening intermediate product, and adding an alkaline for ring closing the ring-opening intermediate product to form the biomass epoxy resin composition, wherein the catalyst includes 0.8 to 8 parts by weight of triphenyl phosphine and 0.01 to 0.1 parts by weight of 4-methoxyphenol.