In order to increase the life of bituminous pavement, quality of bitumen needs to be enhanced and modified. Different dosages of nano-organic montmorillonite (nano-OMMT) were used as modifier for base asphalt. The effect of the contents of nano-OMMT on high temperature performance of asphalt was investigated. Experimental results showed that with the increase of nano-OMMT of content, the high temperature performance of asphalt was gradually improved. And the high temperature sensitivity of asphalt is also enhanced. The nano-OMMT modified asphalt is expected to possess superior rutting resistance to the base asphalt.