Abstract: The maximum force total elongation of HRB600 grade steel bars was tested using the extensometer method and the manual method. The impact of two different testing methods on the test results was analyzed, the uncertainty of the manual method for testing the maximum force total elongation was evaluated. The results show that the results of manual testing for maximum force total elongation were greater than those of extensometer testing for maximum force total elongation. The testing position had a significant impact on the testing results of the manual method. As the distance from the fracture gradually increased, the maximum force total elongation of sample gradually decreased. When the confidence probability of the interval was 95%, the uncertainty evaluation result of the manual method for testing the maximum force total elongation was 4%.