Abstract: Objective　To explore the Influential factors for the position of abdominal aortic bifurcation (AB).    Methods　The vertical distances between AB and the midline, between AB and the inferior margin of L4 vertebra were measured on CT images. Lumbar lordosis angles was measured at median sagittal plane by three different methods. Age of patients, gander and body?mass?index?(BMI) were recorded. Results   With the increasing of age, AB gradually decreased and moved to the right side.  Terminal of aorta in male continued to decline, but in female, there did not show a significant downward shift until the age of 65. There were no correlation  between position of AB and lumbar lordosis, gender, BMI (P>0.05). There was significant correlation  between age and lumbar lordosis (P<0.01).　Conclusions　The descending and rightward end of AB was associated with the age. The findings were helpful for low aorta block.  

Key words: Lumbar lordosis, 　Influencing factors, 　Abdominal aortic bifurcation, 　Imaging investigation