Warm Mix Asphalt is a new kind of material which is a environment friendly one and used to save energy too.It has the same performance as the Hot Mix Asphalt and even better than it.It can be mixed and rolled at a lower temperature than the HMA.So this technology can reduce the cost of energy and decrease the emissions and fumes.This paper makes a study on the technology of reducing the asphalt viscosity based on the Sasobit-modified asphalt for Warm Mix Asphalt for its application in the actual projects,and also makes a study on the normal performance and the rheology of the Sasobit-modified asphalt.