On account of environmental friendliness, high energy conversion efficiency and high 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 technical challenges, which restricts the large-scale commercialization of fuel cell electric vehicles (FCEV). In addition to the complex aging mechanism of PEMFC, the durability and energy relationship of key components in powertrain system, including battery and DC/DC converter, have a crucial impact on the vehicle performance, which have not been thoroughly analyzed. Nowadays, most researchers have explored the causes of components degradation from models or experiments and tried to carry out the life expectancy. Nevertheless, it is in need of system-level researches on durability against the actual automotive application. Therefore, focusing on FCEV and based on the literature research method, latest technologies on main components durability are reviewed in its reasons and improvement strategies. The system-level influence of the energy coupling of main components on the degradation process 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 comprehensive analyses, this paper proposes the development direction of researches on the durability study for FCEVs, and provides helpful guidelines for the durability improvement from system level.