On account of the environmental friendliness, the high energy conversion efficiency and power density, the proton exchange membrane fuel cell (PEMFC) has been used for automotive application for years. However, its durability in powertrain system is one of the technical challenges and it restricts the large-scale commercialization of PEMFC electric vehicles. In addition to the complex PEMFC aging mechanism, the durability and the energy relationship of the powertrain key components, including the battery and DC/DC converter, which have not been thoroughly analyzed, have a crucial impact on the vehicle performance. Nowadays, most researchers have explored the causes of the degradation of various components from the models or experiments and tried to carry out life expectancy. Nevertheless, it is in need of researches on durability against the actual automotive application on system level. Therefore, considering PEMFC electric vehicles and based on the literature research method, latest technologies on durability of key components are reviewed in its reasons and its improvement methods. The influence of the energy coupling on the degradation process of key components on system level is afterwards discussed in detail. Furthermore, the methods of improving powertrain system durability is summarized with a view of offering references for practical applications. Based on the comprehensive analysis, this paper proposes the development direction of the research on the durability study of PEMFC electric vehicles, and provides helpful guidelines for the durability improvement from system level.