Abstract: With image processing techniques, some studies have successfully realized the quantitative description of wax crystal morphology and size. However, few studies focus on the wax crystal particle size distribution characteristics. In this paper, quantitative description of waxy crystal particle distribution characteristics is achieved by referring to the methods and parameters for describing particles group size distribution characteristics in material fields. By using the particle size distribution width coefficient, the wax crystal particles size distribution width is quantitatively characterized. The wax crystal particle diameter in each frequency range is clearly denoted by combining with histogram of wax crystal particles size distribution. The irregularity of waxy crystal particle size distribution is quantitatively expressed by the fractal dimension of wax crystal particle size distribution. The analysis results of wax crystal microscopic images of both virgin waxy crude oil and its corresponding pour-point-depression (PPD) beneficiated oil show that the wax crystal particles size increased, and the particle size distribution width coefficient increased as well after PPD treatment. Moreover, the size distribution turned wider, and the fractal dimension of wax crystal particle size distribution increased.