Experiments on normal section flexural capacity with two groups of five ECC/high strength reinforced concrete composite beams were implemented to explore its flexural characters with different ECC depths. It was found that comparied with steel reinforced beams, composite beams gained more flexural capacity, and had the less deformation and crack width under the same load. Plane-section assumption was still applicable,strains between steel and ECC were also well accorded with, which showed that ECC could bring the high strength steel into full play, while it would happen brittle fracture when the ECC's depth increased to one half of the beam. On the basis above, combined with superposition principle, constitutive model of ECC was been simplified to neglect its stress hardening behavior, a new calculation method for the capacity of the composite beams was proposed. To verify the theory, results by the calculated and the experimented had been comparied.