The boron-containing o-cresol-formaldehyde resin (BoCFR) with different amounts of boron was synthesized from o-cresol, boric acid and formaldehyde solution. The curing process of resin was by characterized by FTIR. The thermal properties and dynamic mechanical properties of resin were investigated. The results show that the borate has formed. The BoCFR has a better thermal stablitity. The residual rate of BoCFR is 30-40 % at 900 oC, which is higher about 400 oC than ordinary o-cresol-formaldehyde resin (o-CFR). The maximal mechanical loss temperature (Tp) is higher 30-38 oC than o-CFR. The weight loss of BoCFR can be main divided two stages. The main thermal degradation reaction follows first order kinetics.