Heat treatment is a commonly-used method to improve the performance of lumber. In this paper,physical and mechanical properties of dimensional lumber of 4 selected Chinese species,treated under 180 ℃and 230 ℃,were evaluated. The results showed that the color of treated lumbers became darker with the increasing temperature. The dimensional stability,compression strength,and modulus of elasticity （MOE） showed considerable improvement. However,modulus of rupture （MOR） and impact resistance decreased when the treated temperature increased.