Abstract: In order to investigate the relation between wax crystal morphology of wax deposit in pipelines and its structural strength, gelling oil with different wax contents was prepared in the lab to simulate wax deposits in the field pipelines. Then, the wax crystal microscopic images which were taken in different experimental conditions were processed by the Image J software. And it is confirmed that these micro images were taken at the temperature of 40 ℃. It is shown that with the increasing of wax content in gelling oil, the particle quantity, area fraction and roundness of wax crystal increase and its aspect ratio decreases. The aspect ratio is mainly distributed in the range of 1.50-2.00, indicating that the wax crystals are mostly in the shape of long rod. Finally, the relation between wax crystal morphology and its structural strength was analyzed with yield stress behavior test of gelling oil. And it is shown that with the increasing of wax content, the bounding fractal dimension and yield stress of wax crystal increase. It is concluded that the morphologic difference of wax crystal inside gelling oil is the fundamental reason why the structural strength of wax crystal varies with the wax content. The research results provide technical support for oil pipeline pigging in the future.