Abstract: The inter-laboratory comparison test of elastic modulus of low carbon alloy steel standard sample was performed in four laboratories by using sample delivery method. The results show that the comparison tests results between four laboratories by using one extensometer, two extensometers, bilateral extensometer and electrical measurement method were all satisfied. By comparing and analyzing the results, it was found that the small deformation measurement accuracy below 0.100 mm should be paid attention to during calibration, verification and intermediate checks of extensometer. When necessary, the correct factors of the indicating values of thesmall deformation should be given. The inter-laboratory comparison test should always be carried out to ensure the testing technical capabilities of the laboratory.