Abstract: By comparing the three known torque multiplier calibration methods in China, the differences in their calibration methods and calculation results are analyzed, and the problems of inconsistent calibration methods, inconsistent calibration data processing, and incomplete evaluation and analysis of results are pointed out. By analyzing the uncertainty evaluation process of the existing torque multipliers, it is pointed out that there are problems of imperfect measurement models and incomplete analysis of uncertainty sources, and the measurement uncertainty evaluation method and process are given with the actual use parameter (magnification) of the multipliers as the evaluation object. The analysis of the evaluation results shows that the measurement uncertainty of the torque multiplier can be reduced when the torque tester measuring the input torque and the output torque is traced by the same superior standard.