Abstract: Objective Many causes can lead to small bowl obstruction (SBO). The aim of this paper is to explore the characteristics of etiological spectrum of SBO and its relation with strangulated small bowel obstruction (SSBO), and provide scientific basis for the management of SBO. Methods The clinical data of 320 adult patients with SBO in our hospital between June, 2010 and September, 2016 were reviewed retrospectively. According to the degree of intestinal ischemia and the pathogeny, the patients were divided into the simple group (non-strangulated group) and the strangulation group (including necrosis subgroup and non-necrosis subgroup). The pathogeny distribution and its relationship to the intestinal strangulation were analyzed. Results Of 320 cases, 107 (33.4%) had adhesions, 73 (22.8%) had external hernias, 46 (14.4%) had volvulus, 32 (10.0%) had internal hernias, 28 (8.8%) had intussusceptions, 7 (2.2%) had tumors, and 27 (8.4%) had other causes. The patients caused by volvulus and intussusceptions in the strangulated group were significantly more than that in the simple group(P<0.05). The patients caused by tumor in the strangulated group were less than that in the non-strangulated group(P<0.05). The number of patients with necrosis caused by external hernias and internal hernias were significantly more than that without necrosis(P<0.05). Conclusion Adhesions is the principal cause of SBO in adults, following by external hernias. Volvulus and intussusceptions tend to cause SSBO in adults. External hernias and internal hernias easily lead to the small intestine necrosis.