Dynamic modeling and anaylzing of partly piezoelectric cantilever system is studied in order to predict, analyze and optimize the performance of discontinuous piezoelectric cantilever system. Firstly, the piezoelectric cantilever is segmented to prensent energy functions, which is substituted into the Lagrange equations to obtain electromechanical motion equation. Secondly, based on boundary conditions and compatibility conditions , calculations method of modal shape and natural frequency is given.Finally, experimental results illustrate that the error of measured frequency of the first and second modal and theoretical model calculations is less than 1%, improving the prediction accuracy of the piezoelectric cantilever system.