Abstract: According to GB/T 228.1-2010 Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature, tensile test was carried out on IF hot-rolled steel plate by WEW-600 universal material testing machine. The sources of uncertainty of tensile test were analyzed, every uncertainty component was evaluated, and finally the expanded uncertainty and the measurement uncertainty report were offered. The results show that the sources of uncertainty of the tensile test mainly included three aspects: testing machine, measuring tools and test results rounding. When the coverage factor k=2, the lower yield strength of the IF hot-rolled steel plate ReL=(264±11) MPa, the tensile strength Rm=(315±13) MPa, and the percentage elongation after fracture A=47.5%±0.3%. This method had certain reference value for uncertainty evaluation of tensile test for metallic materials at room temperature.