OBJECTIVE To study the therapeutic effects of Chaiqin Chengqi Decoction (CQCQD) in treating severe acute biliary pancreatitis. METHODS Ninety patients with severe acute biliary pancreatitis were treated with CQCQD, and they were divided into two groups: early-treated group (54 patients treated with CQCQD within 3 days after the onset of severe acute biliary pancreatitis) and late-treated group (36 patients treated with CQCQD between 3 and 7 days after the onset of severe acute biliary pancreatitis). The complication incidence rate, operation rate, mortality rate and hospitalization period were examined. RESULTS The incidence rates of encephalopathy, infection and gastrointestinal hemorrhage were lower in the early-treated group than those in the late-treated group (P<0.05). The hospitalization periods of the early- and late-treated groups were (24.9+/-18.4) days and (51.6+/-45.9) days respectively (P<0.05). The general mortality rate was 14.4%. The mortality rate of the early-treated group (7.4%) was significantly lower as compared with that of the late-treated group (25.0%) (P<0.05). The operation rate of the early-treated group (11.1%) was also significantly lower as compared with that of the late-treated group (27.8%) (P<0.05). CONCLUSIONS Treating severe acute biliary pancreatitis with CQCQD in early stage may reduce the complication incidence rate, shorten the hospitalization period, and decrease the operation rate and mortality rate.