Abstract: Uncertainty evaluation of tensile test at elevated temperature for metallic materials was carried out by reference to the uncertainty evaluation method of metals at room temperature, and the calculation method of uncertainty caused by temperature fluctuation was proposed. The results show that when evaluating the uncertainty of elevated temperature tensile test according to JJF 1059.1-2012, the linear relationship between temperature and force can be obtained by the least square method after measuring the force changes at different temperatures near the test temperature, the slope can be used to evaluate the impact of temperature fluctuation on the force of samples, and the uncertainty evaluation of elevated temperature tensile test can be well realized.