Abstract: The Brinell hardness of an imported aluminum alloy rod was tested by using XHBT-3000Z Ⅲ automatic Brinell hardness tester, and the measurement uncertainty of the test results was evaluated. By establishing a mathematical model, the standard uncertainty components affecting the test results were determined, and the uncertainty report of the final test results was given. The results show that in the actual test process, the accuracy of the test results can be improved by controlling the maximum uncertainty component.