Abstract: Based on the available theories, centrifuge concrete-filled steel tubular (CCFST) is studied by simplifying it as a kind of composite material. An analytical model for constitutive relationship of CCFST is proposed by using strain energy principle in elastic state and assuming quadratic parabolic stress and strain relationship in the elastoplastic stage. Good agreement is observed between the predictions using the proposed model and the experimental results. The present work has laid down a good foundation for further study of mechanical properties of CCFST and improvement of design methodology.