Abstract: The pre-stress modal analysis of low pressure 333 blade and 633 blade is carried out by the workbench.There are two modes of analysis for each blade.One method considered the contact behavior between adjacent shroud.The other is to calculate the resonance frequency by the shroud imprinting surface method.Both modes change the contact mode of shroud and blade root respectively to simulate the real contact stiffness as much as possible.The resonant frequencies of the blades under different calculation modes are obtained, and the resonant frequencies are compared with the experimental results.The calculation method closest to the test results is found.It provides a reference for the vibration design of subsequent blades.