Abstract: Affected by test condition and experiment period，it is feasible for scholars to study relevant science problems by numerical method based on finite element program OpenSees． The representation method ofRC component mechanical property on fibre level was emphatically discussed by weighting the computational cost and computational accuracy，and the nonlinear beam-column element which was established from the method of finite element flexibility and fiber model was taken as basic unit for finite element analysis，then the bond-slip between reinforcement and concrete was simulated by using zero-length element． Taking advantage of object-oriented programming and open source code in OpenSees program，the time variant characteristics of existingRC structure material could be considered by embedding user-defined material，and then the numerical modeling theory which was proved to be reliable for slightly corrodedRC structure was finally established．