Compare with the conventional proton exchange membrane fuel cells (PEMFCs), high temperature proton exchange membrane fuel cells (HT-PEMFCs) have more advantages such as higher CO tolerance of catalyst, easier water management and higher catalyst activity. As the core component of the HT-PEMFC, proton exchange membrane should have excellent flexibility , thermal stability and high proton conductivity at high operation temperature and anhydrous environments. By atomic force microscope (AFM) technology, the surface topography image and lateral force image of the untreated and treated polybenzimidazole (PBI) membrane are investigated.