Abstract: A composite element model for concrete and reinforcement is adopted in this paper with regard to the characteristic of R.G. shearwall. The local contact effect is taken into account in the concrete model. Both tension stiffening and the Bausinger's effect are considered in the σ-ε relationsof steel.A program for analysing R.C. structures under cyclic loading is worked out on the basis of above ideas. Comparsion with the collected test data and previous analytical results shows that the analytical models used in this paper are more reasonable and accurate. So the method presented by this paper is very useful to understand the behaviors of R.C. structures under earthquake loading.