This paper summarizes the research on physical and mechanical performance of wood exposed to fire at home and abroad. Based on the Lie's theory on fire, the author introduces the calculation and design on fire resistance of timber members such as beams and columns etc, which are 3-sided exposure or 4-sided exposure to fire, and then gives some effective measures to increase the fire resistance of timber structure. A new mechanics-based design method for exposed, large wood members for other loading conditions and fire exposures is also put forward.