Sealing stability in proton exchange membrane fuel cell (PEMFC) is critical to the performance and safety of stacks. However, sealing structure failure (SSF), which leads to the leakage of reactant gases, often occurs in the assembly process or start-up operation for PEMFCs. This study aims to investigate the effects of geometrical structure and material parameters of sealing components on the sealing structure failure. Slippage angle and slippage distance are adopted to evaluate the risk of SSF. Finite element (FE) simulations are conducted with consideration of the assembly process and start-up operation. Experiments are carried out to validate the accuracy of the FE model. Influences of parameters of gasket, membrane electrode assembly (MEA) frame, sealing groove shape of bipolar plate (BPP), and gas pressure are discussed in detail. Meanwhile, the risks of SSF for the stack by using metallic and graphite BPPs are compared. It is demonstrated that material properties and geometrical parameters of sealing components in PEMFC have great effects on SSF. The methodology developed is beneficial to the understanding of the SSF, and it can also be applied to guide the design of PEMFC stack assembly process to keep a good sealing reliability. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.