Abstract: Art optimization procedure for the design of composite laminate structures is offered, considering not only the in-plane macroscopic behaviour, but also the non-uniformity of interlamina stresses. The in- plane modulus and interlamina stress are used as the constraint function and the objective function respectively. The ply-orienttation is optimized with non-linear programming （SUMT method）. Some typical results of optimum design of composite laminates are obtained.