OBJECTIVE To study the sp ectrum-effect relationship of anti-gastric ulcer effect of Shaoyao gancao decoction. METHODS Eleven batches of Shaoyao gancao decoction were prepared ；gastric ulcer model was established by anhydrous ethanol modeling method. Using Weikangling as positive control ，the effects of Shaoyao gancao decoction on the contents of defensive factors [nitric oxide （NO），epidermal growth factor （EGF），superoxide dismutase （SOD）] and attack factor [malondialdehyde （MDA）] in gastric tissue of model rats were investigated. HPLC fingerprints of 11 batches of Shaoyao gancao decoction were established and similarity evaluation was performed with Similarity Evaluation System of Traditional Chinese Medicine Chromatographic Fingerprint （2004A edition ）； common peaks were identified by comparing with mixed control. The spectrum-effect relationship of Shaoyao gancao decoction against gastric ulcer was analyzed based on the grey correlation analysis. RESULTS Eleven batches of Shaoyao ganyao decoction could significantly decrease the content of MDA in gastric tissue ，while increased the contents of NO ，EGF and SOD in gastric ulcer model rats （P＜0.01），and had a certain inhibitory effect on the gastric ulcer. There were 23 common peaks in chromatograms of 11 batches of samples ，and the similarity with the control fingerprint was not less than 0.9. By comparing with mixed control ，7 common peaks were identified ，namely gallic acid （peak 5），albiflorin（peak 9），paeoniflorin（peak 10），liquiritin（peak 12），isoliquiritin apioside （peak 14），isoliquiritoside（peak 15）， glycyrrhizic acid （peak 22）. The average correlation degree of 7 identified common peaks and pharmacodynamic indexes were greater than 0.6，of which peak 22（glycyrrhizic acid ），peak 10（paeoniflorin）and peak 12（liquiritin）had the largest correlation ， and their values were 0.807，0.772 and 0.770 respectively. RESULTS The anti-gastric ulcer effect of Shaoyao gancao decoction is the result of the synergistic effect of multiple components ，among which glycyrrhizic acid ，paeoniflorin and liquiritin may be the main pharmacodynamic components.