To investigate the clinical characteristics of acute colonic diverticulitis. Methods Clinical records of 132 cases defined as acute colonic diverticulitis by abdominal CT, colonoscopy and/or surgery, hospitalized from January 2007 to December 2017 were analyzed retrospectively. Results Among the 132 cases, there were 89 male and 43 female cases (male : female 2.1∶1.0), with a mean age of (51.8 ± 13.1) years old. A total of 119 cases (90.2%) were diagnosed as uncomplicated acute colonic diverticulitis, while 13 cases (9.8%) as complicated acute colonic diverticulitis. The involving locations included cecum and ascending colon in 82 cases (62.1%), sigmoid colon in 23 cases (17.4%), descending colon in 16 cases (12.1%), transverse colon in 8 cases (6.1%), and two parts of the colon in 3 cases (2.3%). Main clinical symptoms included abdominal pain and tenderness in 132 cases (100.0%), and fever in 117 cases (88.6%). WBC increased in 103 cases (78.0%) with an average number of (15.8 ± 5.1)×109/L. CRP increased in 124 cases (93.9%) with an average value of (34.1 ± 15.3) mg/L. There were 124 cases (93.9%) with thickening of the colon wall and 78 cases (59.1%) with higher peripheral fat tissue density in contrast-enhanced CT. All uncomplicated cases were treated by intravenous antibiotics and improved. Among 13 cases of complicated cases, 3 patients treated by intravenous antibiotics alone and improved, 5 patients with abdominal abscess alone and 2 patients with both abdominal abscess and ascites improved by intravenous antibiotics and drainage of abdominal drainage tube. 2 patients with free intraperitoneal gas and 1 patient with abdominal abscess, fistula and ascites underwent laparotomy and improved. No one died in hospital. Conclusion Acute colonic diverticulitis occurs in middle-aged and old men. The most common clinical manifestations were abdominal pain, abdominal tenderness and fever. Abdominal contrast-enhanced CT plays an important role in diagnosis and assessment of the disease. Most of the patients had a better prognosis with no complications.