Objective To build a recognition mode of Yang deficiency syndrome according to indexes of clinical routine examinations of patients with coronary heart disease unstable angina（UA）. Methods The basic data

traditional Chinese medicine（TCM） four-diagnosis information and clinical routine examination indexes of 411 UA patients were collected. TCM syndrome or syndrome elements and syndrome differentiation were judged by doctors. After data normalization

90 clinical routine examination indexes were taken as independent variables

and "yang deficiency syndrome"was taken as dependent variable. The recognition rules of yang deficiency syndrome were automatically extracted by chi-square automatic interaction detection（CHAID） decision tree method

and the sensitivity

specificity and accuracy rate of the model were calculated. The verification of recognition mode of yang deficiency syndrome on212 included patients was conducted. Results D-dimer

platelet distribution width（PDW）

free tetraiodothy roine T4（FT4）

lipoprotein（a）（LP（a））

chloridion（CI） and prothrombin time（PT） were selected into the decision tree model. The test results of 411 patients of the model showed: sensitivity was 74. 7%

specificity was 72. 6%

and the accuracy rate was 73. 0%. The verification of association patterns lacks Cl

and its accuracy rate was 81. 1%

sensitivity was 74. 3%

and specificity was 82. 5%. Conclusion CHAID decision model could be used to conduct recognition of yang deficiency syndrome of coronary heart disease UA clearly and directly based on clinical routine examination indexes

and to extract recognition rules automatically.