To evaluate effect of heating temperature and duration on brittleness properties of heat treated masson pine（Pinus massoniana）, the specimens were treated at temperatures between 170 ℃ to 230 ℃and heating duration between 2 to 8 hours, then subjected to a static bending test. Results revealed that the main reason for brittleness increase was reduced plasticity. In contrast, elasticity of heat treated samples was hardly affected. Brittleness of untreated masson pine was 22.26%, and increased to 33.64% ,8,9.01% after heat treating. No brittle failures of the control specimens were observed, while more than half the specimens showed brittle failures when treated at 230 ℃ for 6 or more hours.