Development of polymer electrolyte fuel cells (PEMFCs) is recognized as an efficient way to eliminate the energy crisis and environmental pollution issues due to its cleanness and high utilization efficiency of hydrogen. As the key components of proton exchange membrane polymer, electrolyte membrane is a hot research topic. Due to the thermal stability and easy functionalization, polyhedral oligomeric silsesquioxane (POSS) is widely used as filler to enhance the mechanical property and proton conductivity of the hybrid membrane. In this work, the progress in the utilization of POSS in polymer electrolyte membrane was reviewed and the mechanism of enhancements in mechanical property and proton conductivity by POSS was illustrated. This review offers useful information for the design and application of hybrid membrane.