A method for preparing a phenol-formaldehyde resin is provided. The method includes extracting a biomass pyrolysis oil to obtain a first phenolic mixture, mixing the first phenolic mixture, furfural and an alkaline catalyst to proceed to a first polymerization reaction to form a phenol-formaldehyde resin precursor solution, and adding the alkaline catalyst to the phenol-formaldehyde resin precursor solution to proceed to a second polymerization reaction to form a phenol-formaldehyde resin solution. The disclosure also provides a resin material prepared from the phenol-formaldehyde resin. The disclosure further provides a method for preparing a resin molding material.