Objective To probe the value of lactate dehydrogenase combined with BISAP scoring system in predicting the acute pancreatitis complicated by persistent organ damage by means of comparing with Ranson and BISAP scoring system. Methods A total of 200 consecutive patients, who were admitted into the First Affiliated Hospital of Soochow University from December ,2011 to August,2012, were studied retrospectively. 24 hours (BISAP score), 48 hours (Ranson scores)and serum lactate dehydrogenase recorded after admission. Using LDH and BISAP scoring as concomitant variables , we established the prediction model by binary logistic regression analysis, then got the prediction probability(pre).We examined the value of three kinds of scoring systems in predicting persistent organ damage by using the area under the receiver operating characteristic curves(AUC). Results Among these 200 patients，there were 31cases（15.5%）occur persistent organ damage. The AUC of Ranson、BISAP and LDH combine with BISAP scoring on predicting persistent organ damage were 0.931(95%CI0.881-0.962), 0.903(95%CI0.853-0.940), 0.928(95%CI0.883-0.960) respectively. he difference, between LDH combined with BISAP scoring and Ranson scoring was not significant(P=0.926), Thowever，LDH combined with BISAP displayed significant advantages over BISAP alone(P=0.035). Conclusion LDH combined with BISAP scoring was better more than BISAP scoring in predicting persistent organ damage of AP, and also the difference was not statistically significant compared with Ranson scoring. LDH combined with BISAP scoring is a simple，prompt，economical，and ideal prognosis scoring system in clinical practice．