To study the fire resistance performance of timber, 20 Chinese larch specimens exposed to fire were tested, half of which were painted with fire retardant agent and another half were not treated. The thicknesses of charring layers after different burning duration were measured and charring rates were obtained by linear regression method. Then the parallel to grain compression tests were conducted with the fired specimens. The results show that the strength of timber parallel to grain decrease after fire, and a linear expression can be used to describe the bearing capacities of remaining sections versus burning duration. The test results also show that the fire retardant agent by the brushing method used in the research can retard charring rate at the early stage, but it is almost useless to rescue the strength loss.