Dimension lumber (cross sections are 40mm×65mm, 40mm×90mm and 40mm ×140mm, length is 4000mm) of Chinese larch(Larix gmelini) was visually graded intoⅠc, Ⅱc, Ⅲc and Ⅳc according to GB 50005—2003 standard, and was tested according to ASTM D4761 02a. The characteristic values of modulus of elasticity(MOE), modulus of rupture(MOR), ultimate tensile strength(UTS) and ultimate compressive strength(UCS) were estimated using nonparametric statistical analyses according to ASTM D2915 03. The characteristic strength value of Chinese larch is larger than that of Spruce Pine Fir(S P F) dimension lumber. The characteristic strength value was obtained and deduced from small sample of clear wood in GB 50005—2003, so that the situation was changed. The scientific method for estimating the characteristic strength of dimension lumber can be used to dimension lumber of other species in China.