Objective:To explore the efficacy and mechanism of modified Da Chengqitang in treating hyperlipidemic acute pancreatitis （HLAP） with damp heat accumulation syndrome. Method:A total of 110 patients with HLAP with damp heat accumulation syndrome treated at our hospital were randomly divided into control group and observation group， with 55 cases in each group， both groups were treated with low molecular weight heparin calcium， insulin and alprostadil injection. Control group was given Huazhironggan granules in addition to the basic therapy， while observation group was given modified Da Chengqitang in addition to the basic therapy. After 7 days， the clinical efficacy， traditional Chinese medicine (TCM） syndrome score， gastrointestinal function recovery， acute pancreatitis bedside index （BISAP）， acute physiology and chronic health status Ⅱ （APACHE Ⅱ）， inflammatory factors， such as tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6） and C-reactive protein （CRP）， oxidative stress， such as malondialdehyde （MDA）， oxidized glutathione （GSSG）， total antioxidant capacity （T-AOC）， total cholesterol （TC）， triglyceride （TG）， high and low density lipoprotein （HDL-C， LDL-C） blood lipid indicators and safety were evaluated. Result:The clinical efficacy of observation group was significantly better than that of control group （Z=3.353， P<0.05）， and the total effective rate of observation group was 94.55%， which was higher than 74.55% of control group （χ²=8.419， P<0.01）. After treatment， the scores of abdominal pain， stool obstruction， chest tightness and fever in observation group were significantly lower than those of control group （P<0.05）. The gastric tube indwelling exhaust time， defecation time and recovery time of bowel sounds in observation group were significantly lower than those of control group （P<0.05）. The scores of BISAP and APACHE Ⅱ in two groups were significantly decreased， and the BISAP and APACHE Ⅱ scores of observation group were lower than control group （P<0.05）. After treatment， the serum levels of TNF-α， IL-6 and CRP in observation group were significantly lower than those in control group. The levels of serum MDA， GSSG in two groups were significantly decreased， whereas the T-AOC level was significantly increased； and the level of serum MDA， GSSG observation group was lower than control group， while the T-AOC level was higher than control group （P<0.05）. After treatment， the levels of TC， TG and LDL-C in two groups were decreased， while the level of HDL-C was increased， the levels of TC， TG and LDL-C in observation group were lower than those in control group， and the HDL-C was higher than that control group （P<0.05）. Conclusion:modified Da Chengqitang has a definite clinical efficady in treating HLAP with damp heat accumulation syndrome， and can alleviate TCM syndrome and patient symptoms， reduce inflammatory factors， inhibit oxidative stress of the body. It has a good safety， and is worthy of clinical application.