Abstract: In order to further improve the accuracy of the impact strength test of alcohol modified PET copolyester (PETG) cantilever beam, the influencing factors in the test process were analyzed. The influencing factors such as standard, test equipment, spline size, notch forming process and its size, blade clamping method, personnel, environment, component type and content were mainly analyzed. Various influencing factors were tested and evaluated, and 10 different PETG were compared. The results show that the standard deviation, notch forming process and its size, blade clamping method, component type and content had significant effects on the determination of impact strength of PETG cantilever beam. For example, the relative standard deviation of PETG impact strength test results could be reduced from 15.90% to 3.57% after the blade clamping method was optimized. The impact strength of 5 kinds of 1,4-cyclohexanedimethanol PETG cantilever beams was basically 41-62 J/m. The impact strength of the five kinds of PETG cantilever beams was basically 85-112 J/m, and there was a significant difference between the two.