Considering the rapid global convergence of the particle swarm optimization(PSO) algorithm and the strong optimization ability of the ant colony optimization(ACO) algorithm,the hybrid algorithm was put forward by combining with PSO algorithm and ACO algorithm.The optimal location values of the particles were generated by the strong global searching capability of the PSO algorithm.The total number of the ants was adjusted to ensure the global searching ability of the ACO algorithm and avoid trapping in local optimum.With the modified ACO algorithm,the optimal location values were further optimized.The hybrid algorithm is used to the optimization design of the light steel structure,and the design model was established.For an example,the wrap-round frame with light steel was optimized.By comparing to the optimization of the modified simulated annealing algorithm in literature the results showed that the hybrid algorithm which solved the global optimal solution after 61 iterations,was feasible,