Asphalt binder viscosity tests and mixture compaction tests were conducted to explore a reasonable method for the determination of the mixing and compaction temperatures for warm mix asphalt (WMA) with Sasobit additive for paving roads. Test results and result analyses have indicated that the traditional binder equiviscous principle is not applicable to Sasobit mixture due to the significant underestimation of the temperature-decreasing effect of the additive. A mixture equivolumetric principle was proposed, which is applicable to both neat binder and Sasobit mixtures to determine the compaction temperature. For neat binder mixture, the temperature determined by using mixture equivolumetric principle is essentially the same as that determined by using binder equiviscous principle. For Sasobit mixture, the temperature determined by using mixture equivolumetric principle is consistent with those recommended by the manufactures and those in practice to date. In view of the fact that influencing factors have little effect on the differences between the apparent viscosity and the actual flow ability, assumptions were also proposed to determine the upper and lower limits of mixing and compaction temperatures.