Abstract: Objective To investigate Value of 128 multi-slice spiral CT angiography(MSCTA)in diagnosis of left renal vein entrapment syndrome in children. Methods MSCTA was used to measure the angle between superior mesenteric artery(SMA)and abdominal aorta(AA)in 30 children with left renal vein entrapment syndrome. The inner diameter of left renal vein stenosis between SMA and AA, the dilation diameter near renal hilum, the ratio of the two diameters above, cross-sectional area ratio, the volume difference of two kidneys, body mass index, and the results were compared with those in the control group. Results The average angle between SMA and AA was(16.70±0.31)in 30 patients with left renal vein entrapment syndrome, the internal diameter of LRV passing through the narrow segment of SMA and the dilation inner diameter of the left dilated segment near the renal hilum were(0.29±0.02)cm and(1.15±0.04)cm, respectively. The ratio of above internal diameters was(4.89±0.53), the ratio of cross-sectional area was(3.30±0.11), the volume difference between left and right kidney was(16.10±2.20)cm³, and the body mass index was(15.90±0.44)kg/m², which showed a significant difference compared to the control group(P< 0.01). Conclusion MSCTA imaging is of great clinical value in the diagnosis of left renal vein entrapment syndrome due to its advantages of non-invasive, wide scanning range and multi-plane and multi-angle imaging and can be an accurate, simple and effective method in diagnosis left renal vein syndrome.