In this study, organomodified montmorillonite (OMMT) modified asphalt was used in porous asphalt, and fatigue characteristics of the mixtures with or without OMMT were investigated. Special attention was paid to the beam specimens aged in a forced draft oven at 60°C for 500h. Basic fatigue information, such as stiffness, dissipated energy of the material, was obtained through four-point bending beam testing under different controlled strain. The classical fatigue life definition was used to evaluate fatigue resistance of different mixtures. The research results indicate that the OMMT mixture exhibits better fatigue and ageing resistance than the neat one. It is suggested that OMMT should be an excellent alternative for the durability of porous asphalt.