The development of a steel material model in order to follow the cyclic plastic behaviour is essential in seismic design. The authors present an improved Chaboche model for the cyclic mechanical behaviour of structural steel. The model is based on the combination of nonlinear kinematic and multi-linear isotropic hardening with a parameter refreshing method. This model can consider the different physical phenomena of steel bahviour under cyclic loading. The developed model is verified by experimental results; the calculation of model parameters, the effect of the applied constants and the calibration are discussed.