Abstract: Objective To analyze the chest CT imaging features of AP and explore the clinical value of diagnosis and prognosis for acute pancreatitis. Methods Using the new standard of Atlanta for Acute Pancreatitis, 130 cases AP were divided into two groups, mild acute pancreatitis (MAP, 80 cases) and severe acute pancreatitis (SAP, 50 cases). The patients of clinical and CT features were analyzed. Explore bilateral pleural effusion thickness and lung consolidation thickness at mediastinum window of chest transvers CT and investigate results with the scores of CTSI,EPIC,BISAP and APACHE-Ⅱ. Results The chest CT of SAP manifested:The percentage of bilateral pleural effusion, pulmonary consolidation in SAP was more than in MAP, while the percentage of single pleural effusion,pulmonary consolidation and negative damage in SAP was less than in MAP. There was no significant difference between two groups (P>0.05).The ratios among left pleural effusion/chest thickness, left pulmonary consolidation/chest thickness and right pulmonary consolidation/chest thickness in SAP were more than in MAP, There were significant differences between two groups (P<0.05). There were significant differences among different groups about CTSI score, EPIC score, BISAP score and APACHE-Ⅱscore (P<0.05).After comparison each two groups, there were significant differences among some groups for all scores, especially in the EPIC score and BISAP score.There was middle-grade positive correlation among bilateral pleural effusion and pulmonary consolidation with EPIC score、BISAP score (P<0.05);there low-grade positive correlation with CTSI score、APACHE-Ⅱscore (P<0.05).About the hospital stays, there was no significant differences among all groups, but there were significant differences between group 1 and group 5.AP with double pleural effusion or pulmonary consolidation died each one, the mortality were 1.5%and 1.1% respectively, while single pleural effusion or pulmonary consolidation died no one. There was no significant difference between them (P=1.000). Conclusion Bilateral pleural effusion/pulmonary consolidation suggest SAP to some extent. Measuring the values of pleural effusion/pulmonary consolidation has some clinic cost for assessing the severity and the prognosis of Acute Pancreatitis.