There are more than 700 different bacteria colonized in human oral cavity, which are collectively referred to as oral microbiota. Emerging evidence suggests that oral microbiota plays a series of important roles in human health, such as immune response, carcinogen metabolism and nutrient digestion. The changes of oral microbiota composition are closely related to the occurrence and development of pancreatic diseases. Previous studies have found that there are dense bacterial biofilms in the pancreatic duct of patients with calcified pancreatitis, including oral bacterial types. However, most studies only focused on the changes of gut microbiota in patients with chronic pancreatitis, and there were lack of research and description on the changes of oral microbiota in patients with chronic pancreatitis. In this study, we will extract and sequence bacterie's full-length 16S rRNA to describe the characteristics of oral microbiota in patients with chronic pancreatitis, confirming that there are changes in oral microbiota in patients with chronic pancreatitis, and compare the differences of oral microbiota in patients with chronic pancreatitis, pancreatic cancer and autoimmune pancreatitis.