Abstract: OBJECTIVE To investigate into the regularity of syndrome classification for chronic atrophic gastritis(CAG) using structural equation model(SEM).METHOD Epidemiological method was adopted to collect the information of the CAG patients based on the four diagnostic method and data of the pathological features of the disease based on gastroscope examination.Structural equation models were built by means of multidimensional indexes of disease feature and apriorism.RESULT Among the 22 indexes of syndrome differentiation,4 potential dependent variables were extracted,corresponding respectively to the four common syndromes: damp heat of the spleen and stomach,incoordination between the liver and stomach,deficiency of the spleen and stomach and deficiency of stomach yin,which were respectively correlated to the information of dominant four diagnostic methods.Each of the four dependent variables was affected by a potential independent variable,which reflected the common property of CAG.CONCLUSION There are four most common CAG syndromes correlated to the corresponding syndrome differentiation indexes,with differences in the intensity of their correlation.In this study,the common symptoms are epigastric pain and poor appetite,which conforms to the reality of TCM clinical practice.SEM analysis shows that this method is practical in the explanation of the presence of TCM syndromes of specific diseases and the method of their measurement.