In order to improve properties of fast-growing poplar wood, the authors developed a combined process of sodium silicate solution impregnation and heat treatment to modify the wood. The effects of modulus of sodium silicate and treating process on properties of the modified wood samples were discussed. The results showed that it was the most effective process to use the sodium silicate solution with modulus 3.3 and a heating treatment at 210 ℃ for 2 hours for improving the overall physical and mechanical properties of the wood.