For the damping optimization of composite structures with multi-interleaved viscoelastic layers,a computational model is built for the loss factor by the energy method, in which the strain energy stored in the in-plane as well as in transverse shear is considered,and its deflection function is assured to be perfect by means of an experimental method. The optimization goal is the maximum of the loss factor of composite structures with multi-interleaved viscoelastic layers. Optimization designs are made of a single variable and multi-variables optimization for the loss factor by improved genetic algorithms. The numerical results show that the improved genetic algorithms are available for the damping optimization design of composite structures with multi-interleaved viscoelastic layers, and that the multi-variable optimization design is better than single variable optimization design. After the damping optimization design, the loss factor of composite structures with multi-interleaved viscoelastic layers is improved from the original result of 0.184 to 0.287.