The low temperature force-ductility performances of SBS,SBR,EVA,PE polymer modified asphalts were studied by force-ductility tests.The effects of polymer type and polymer content on low temperature force-ductility performances including elongation,max force and toughness were investigated.Test results show that max force in force-ductility curves enhances with the increase of the content of PE or EVA while the content of SBS or SBR has light influence on max force.Toughness of polymer modified asphalts improves significantly with the increase of the content of SBS or EVA.Toughness of polymer modified asphalts measured by force-ductility tests has a good correlation with creep stiffness(CS) by bending beam rheometer(BBR) tests,which indicates toughness is of value to evaluate the low temperature performances of polymer modified asphalts.