Based on discrete material optimization and topology optimization technology, considering the characteristics of discrete variable of fiber ply angle in fiber reinforced composites, the paper discusses the problem of integrated design optimization of materials and structure of composite plates and shells.An optimization model based on minimum structural compliance with specified composite volume constraint is established.The ply angle and distribution of the composite material are introduced as the independent variables on the two geometric scales (material and structural scales).The void material is added into the optional discrete material database to realize the topology changes of the structures.The paper proposes an improved HPDMO(Heavisde Penalization of Discrete Material Optimization) model, and the explicit sensitivity analysis is carried out via the direct method based on this model.The influences of classical Discrete Material Optimization model, Continuous Discrete Material Optimization model and the HPDMO model on the convergence rate of optimization results, value of objective function and iteration history are studied in the paper.Numerical examples in the paper show that the HPDMO model not only can effectively achieve the integrated optimization of fiber ply angle and distribution in structural domain, but also improve the convergence rate of the optimal results considerably compared with other DMO model and thus reduce the cost the manufacture of the optimal design.