Abstract: Boronmodified walnut shell biomassbased phenolformaldehyde resins (BWPF) were synthesized by solidphase generation method with the liquefied products of walnut shell in phenol, plus boric acid and paraformaldehyde as raw materials. The structure and properties of BWPF were analyzed by Fourier transform infrared spectra (FTIR), the morphology of its natural cross section was observed by scanning electron microscope (SEM), whereas its thermal properties were analyzed by differential scanning calorimeter (DSC) and thermogravimetric analysis (TG). The results showed that a new crosslinked bond such as BO was formed in the process when boric acid reacted with the phenolic hydroxyl groups in the liquefied products of walnut shell.With the increment of boron content,the toughness and curing temperature of BWPF were both promoted. The carbon residual mass and thermal stability of the resins were all increased with the increasing of the boric acid amount, reaction temperature and reaction time duration.