Objective To investigate the etiologic effect of the lumbar facet joint morphology on the occurrence of degener?ative lumbar spondylolisthesis (DLS). Methods From January 2007 to July 2013, 115 patients with DLS treated in our hospi?tal were randomly selected. There were 28 males and 87 females with an average age of 57.3 years (range, 41-76 years). 115 age? and sex? matched people including 31 males and 84 females with an average age of 56.4 years (range, 45-77 years) free from DLS and back or leg pain were selected randomly as control group from a group coming for routine physical examination in our hospital. Both groups received lumbar anteroposterior and lateral X?ray films、CT scanning and multiplanar reformation, the degree of spondylolisthesis (Taillard index) was measured in DLS group on lateral radiographs; at L3,4 and L4,5 level of both groups the facet joint angles on CT scan images were measured and facet tropism was evaluated, the pedicle?facet angle (the P?F angle) was measured in the sagittal plane on multiplanar reformation CT images, and then all angles of corresponding level were compared and analyzed; L4,5 facet joint degeneration in both groups was evaluated and compared in bone window, the de?gree of spondylolisthesis (Taillard index) in DLS group at different degenerative grade of facet joints were analyzed. The corre?lation between L4,5 facet joint angle、P?F angle and degrees of spondylolisthesis were analyzed. Results All L4,5 spondylolisthe?sis in DLS group were grade I, the facet joint angles were more sagittal in DLS group than those in the control group at L 3,4 and L4,5 levels, and the P?F angles were more horizontal in DLS group compared with control group;the facet tropism in DLS group at L 4,5 level were significantly different as compared to the control group, but there was no significant difference at L 3,4 level between the two groups. Significant difference was found in L4,5 facet joint degeneration grade between two groups,but there was no significant difference in degree of spondylolisthesis during different degeneration grades in DLS group. There was no significant correlation between the facet joint angle and the P?F angle and degree of spondylolisthesis at L4,5 level in DLS group. Conclusion The facet joint morphology abnormality (smaller facet joint angle, horizontal P?F angle, the facet tropism) has an important etiologic meaning in the occurrence of degenerative lumbar spondylolisthesis, however its role cannot be excessively exaggerated. The facet joint de?generation is a secondary change with aging,while the development of DLS aggravates the degeneration.