Abstract: Taking West Crude Pipeline transporting blended TuHa Crude and Kazakhstan Crude, with ultra-high set point in head of tender and tail of tender in 2008 as an example, DSC (differential scanning calorimetry) technique is used to analyzed the property mutation reason for the PPB-injected crude oil. Parameters in wax deposit point, wax deposit peak point and wax deposit enthalpy content of the oil were measured and wax content was calculated based on the result measured.