Abstract: Mettler Toledo RC1e calorimeter was used to investigate the thermodynamics, fluid property and the heat treatment mechanism for Daqing Waxy Crude Oil. Through the in-situ measurement, the dynamic changes of specific heat and viscosity were detected during temperature increase and decrease. It is observed that different varying trends was existed at three temperature intervals during the heat treatment (above pour point 8~10 ℃, 10~15 ℃ and 15 ℃). At different temperature interval, there were two major factors for specific heat change. One was the wax dissolving and scattering status, the other was the micelle structure variation and scattering status. Those varying trends in three temperature intervals proved the specific heat changes, and reflected the influence of heat treatment on crude oil system. The heat treatment mechanism for crude oil was investigated by correlating the specific heat and viscosity.