Abstract: The source of the uncertainty of measurement in metallic materials at room temperature tensile test was analyzed, and the uncertainty of measurement of the metallic materials at the room temperature tensile test was evaluated by establishing mathematical model and repeatability test. The results show that as a standardized testing laboratory, under the controlled conditions of man, machine, material, method, environment and management, and under the condition of containing factor k=2, relative expansion uncertainty of lower yield strength U_rel (R_eL)=2.9%, relative expansion uncertainty of tensile strength U_rel(R_m)=1.6%, relative expansion uncertainty of elongation after fracture U_rel(A)=2.8%, relative expansion uncertainty of section shrinkage rate U_rel(Z)=2.1%. The evaluation method adopted in this paper provides reference for the evaluation of uncertainty in measurement of metallic materials at room temperature tensile test.