Lifetime evaluation and prediction of proton exchange membrane fuel cells (PEMFCs) are essential for the lifetime extension and commercialization of fuel cells. Under the background that the accelerated stress test (AST) is difficult to evaluate the lifetime accurately, and the actual road test is time-consuming and costly, it is necessary to propose a quick lifetime prediction method of fuel cells. In this study, the current degradation law is analyzed based on the first-order kinetic model, and the lifetime prediction method based on the current degradation law is proposed. Moreover, the scale factor k is proposed to completely describe the fuel cell degradation due to complex degradation causes, and its calculation and selection methods are discussed. Finally, the accuracy of the proposed method is verified by the experimental results of single cells and fuel cell stacks, and the maximum relative error is less than 5% when the fuel cells conform to the first-order kinetic model. The lifetime prediction method of PEMFCs based on current degradation law improves the utilization of degradation information in current density, which is a feasible way for automotive fuel cell lifetime evaluation and prediction.