The introduction of new energy vehicles has increased the demand for highly reliable chips, which makes chip aging analysis more and more important. Yet characterization of aging effects usually requires a large amount of test data, which consumes both device and test time. Therefore, a dependable aging test method is proposed in this paper. By determining the stress voltage for accelerated aging and corresponding test time according to the median degradation of device electrical indicators in the pretest. Conclusively, the aging model obtained by fitting the NMOS device test data is simulated and compared with the results of traditional test method based on the same aging time. It proves that the accuracy of this method and its practicality while reducing the cost of aging test.