To eliminate the errors influence of repeat modal shape solutions of brake disc with rotation symmetry characteristic on the calculation of Cross Modal Assurance Correlation (Cross MAC), experimental modal analysis and finite element modal analysis about brake disc were performed to identify each corresponding modal parameters, among which the vectors of modal shapes were reset utilizing cyclic group and elementary rotation transformation severally. The correlation analysis results of finite element modal analysis and experimental modal analysis showed that all the values of Cross MAC of the first nine frequencies approximated to 1, verifying the correlation accurately. All these illustrated that the two modal shape reset methods of cyclic group and elementary rotation transformation were effective to the modal correlation analysis of rotationally periodic structures.