Abstract: Daqing Crude Oil is a typical high gelling point, high viscosity and high wax crude, and its fluidity at low temperature is relatively bad. In order to improve its low temperature fluidity, composite nanometer-sized material is added into the crude. Based on XRD scanning experiment and POM photography, the impact of composite nanometer-sized material on crystal form of paraffine in waxy crude oil and wax precipitation point is studied. Dynamic temperature drop XRD scanning comparison testing on Daqing Crude Oil and its samples with 50 g/t EVA and with 100 g/t composite nanometer-sized material is carried out. Laboratory results show that the composite nanometer-sized material can significantly improve the crystal form of crude paraffine (crystal form of 60.01% n-alkane in crude is effectively modified). It decreases the dimension size of the crystal particle and enlarges the distance between crystal faces. Besides, the wax appearance temperature is dropped distinctly. Therefore the low temperature fluidity is substantially improved, so does the fluidity stability in a long term. In summary the composite nanometer-sized material is better than traditional EVA agent in terms of its capacity to decrease the wax appearance temperature and viscosity.