The non-linear contact prestress modal analysis mechanism of aero-engine shrouded pretwist turbine blade was introduced. The modal analysis of a turboshaft engine power turbine blade was carried out on the platform of ANSYS software. The results showed that the first order frequencies of 9-13 nodal diameter of blade blisk obtained by non-linear contact prestress modal analysis method were consistent with dynamic stress test frequencies

and the difference was basically stable at about 12%-13%. The results indicate that the calculation accuracy is improved obviously compared with the traditional method.