To identify whether the products failure mechanism in accelerating tests is changing, a testing method of failure mechanism consistency of Weibull life distribution based on the principle of acceleration factor constancy is studied.Weibull distribution is converted to I-type extreme value distribution.A method for statistical testing of the scale parameters in extreme value distribution is studied by using Ansari-Bradley method.By using Arrhenius acceleration model, t statistic is constructed based on the least squares method and characteristics of regression coefficients.Statistical testing of the acceleration factor and distribution parameters is implemented, and the stress under which the failure mechanism will change is distinguished.Simulation results show the effectiveness of the proposed method.