As previous work reported that splitting strength of warm mix asphalt with Sasobit is lower. Surface free energy of asphalt with different Sasobit warm mix agent content (0%, 2%, 3%, 4%, by mass) was measured by the sessile drop method, and influence of Sasobit warm mix asphalt surface free energy and related parameters was analyzed. Corresponding to asphalt mixture Marshall test specimen in different Sasobit warm mix agent contents, splitting strength and freeze thaw splitting strength were measured. Finally, relationship between asphalt surface free energy and splitting strength of asphalt mixture in different Sasobit warm mix agent contents was analyzed. The results show that polar component of asphalt and splitting strength is negatively correlated, but dispersion component is positively correlated; and Sasobit makes dispersion component of asphalt reduce, but polar component increase, so splitting strength of mixtures with Sasobit reduces legitimately.