Objective To analyze the diagnosis and treatment value of emergency colonoscopy in acute lower gastrointestinal bleeding. Methods A total of 94 patients with lower gastrointestinal bleeding who were treated between February 2015 to February 2017 were retrospectively analyzed. The patients were divided into observation group (56 cases) and control group (38 cases) according to the examination methods. Observation group was given emergency colonoscopy, and control group was given routine colonoscopy. The causes of bleeding in 94 patients were counted. The detection rate of first bleeding was compared between the two groups. The bleeding volume, blood transfusion volume, time consumption, hemostasis rate and hospital stay were compared between the two groups. Results The probability of acute lower gastrointestinal bleeding caused by colon cancer and colon polyps was significantly higher than that of other unexplained causes (P<0.05). The detection rate of first bleeding in observation group was significantly higher than that in control group (P<0.05). The bleeding volume and blood transfusion volume during examination in observation group were significantly lower than those in control group (P<0.05), and the time consumption of examination in observation group was shorter than that in control group (P<0.05), and the hemostasis rate in observation group was significantly higher than that in control group, and the hospital stay after diagnosis and treatment was shorter than that in control group (P<0.05). Conclusion Emergency colonoscopy can more accurately diagnose the cause of patients with acute lower gastrointestinal bleeding, and it has high detection rate of first bleeding