Considering the randomness of seismic loads and the serious defects brought by the adoption of some particular seismic wave excitation in the structural control simulation,the maximum inter-layer displacement was chosen as the control index and based on the probability density evolution theory,a modified genetic algorithm was proposed to optimize TMD parameters.In the developed method,the improved genetic algorithm was combined with the probability density evolution method,and the nature of the effect of randomness on the structure was taken into full consideration.The superiority of the optimization method was illustrated by the comparison between the inter layer displacement response and the dynamic reliability under random loads of the original and optimized structure-TMD systems.A three-layer shear concrete frame structure with TMD system was given as an example to verify the correctness of the proposed method,which provides a new way for the optimal design of the structure-TMD systems under stochastic excitation.