Abstract: Objective: To investigate the effect of different contrast media injection rates on the imaging quality of multi-slice spiral CT direct iliac vein imaging in order to find the optimal injection rate. Materials and Methods: Between September 2015 and January 2017, 150 patients with suspected iliac vein disease were randomly divided into 5 groups. And the iliac vein CT imaging was performed at the injection rate of 1.5 mL/s, 2 mL/s, 2.5 mL/s, 3 mL/s and 3.5 mL/s respectively. The original data were graded after CT image post-treatment for each patient. From the image development quality, contrast, with or without "edge flow phenomenon" and whether the disease can make the correct diagnosis of four aspects of the evaluation. The CT values of the external iliac vein in each scoring group were measured and the mean value was calculated. The results of each evaluation group were statistically analyzed. Results: The rate of 2.5 mL/s group and 3.0 mL/s group, the difference was not statistically significant, but compared with the other three groups, the difference was statistically significant; 1.5 mL/s group, 2.0 mL/s group and 3.5 mL/s were compared, the signiftcance of adjustment was greater than 0.05, the difference was not statistically significant. The mean CT values of iliac vein in each evaluation group were analyzed by variance analysis P<0.05, 1-2, 1-3, 1-4, 2-3, 2, 4, 3, 4 The results of the comparison group were 4.89, 4.94, 5.30, 4.35, 5.02, 4.67 respectively. P were <0.05, the difference was statistically significant. The correlation coefficient between the CT value of the iliac vein and the score group was 0.87, P<0.05. Conclusion Considering the image quality, patient's tolerance and personal safety and other factors, the rate of 2.5 mL/s is the best rate of multi-slice spiral CT direct iliac vein imaging.