Abstract： Objective To investigate the clinical manifestations, etiology and risk factors of chronic pancreatitis guided by the M-ANNHEIM classification of chronic pancreatitis and to evaluate the validity and clinical significance of this classification. Methods A review of clinical data of inpatients in our hospital from December 2007 to December 2009 was conducted. The classification was carried out according to the pancreatitis were enrolled. There were 256 adult patients and 51 children and adolescent patients (age of onset<18 yr). Among these cases, 129(42%) reported a drinking history. 110 cases (35.8%) had a smoking history, 31 cases (10.1%) presented with hyperlipoidemia. 12 cases had some factors related to pancreatic duct such as pancreas divisum, pancreas trauma. There were 231 (75.2%) cases with calcification of pancreas, 45 (14.7%) with exocrine insufficiency (steatorrhea), 58 (18.9%) with endocrine dysfunction (diabetes mellitus), 32 (10.4%) underwent pancreatic surgeries, and 39 (12.7%) with pancreatic pseudocysts, biliary obstruction, pancreatic cancer and other severe complications. The M-ANNHEIM clinical staging of chronic pancreatitis was: no case in stage 0, 220(71.7%) cases in stage Ⅰ , 69(22.5%) cases in stage Ⅱ ,12(3.9%) cases in stage Ⅲ and 6 cases in stage Ⅳ. The mean value of the M-ANNHEIM score and severity index was 7.78,69 (22.5%) cases were in the minor level, 174 (56.7%) were in the increased level,62(20.2%) cases were in the advanced level. Conclusions The M-ANNHEIM classification of chronic pancreatitis is a simple, objective, accurate and noninvasive tool in clinical practice. This new classification system will be helpful for investigating the impact and interaction of various risk factors on the course of the disease.