This paper proposes an inverse method to obtain the elastic properties of material. The sum of the squared differences between the experimental resonance frequencies and calculated resonance frequencies from the finite element method is chosen as the objective function. The proposed method presents an optimization method, Hybrid Genetic /Simulated Annealing algorithm, to determine the elastic properties. When the objective function reaches its minimum value, its corresponding design variables are the elastic constants of the material. The inverse method is applied to determine the elastic constants of aluminum plate, Glass/PP laminate, and double coated steel plate .The results indicate that for few elastic constants as an aluminum plate, Hybrid Genetic /Simulated Annealing algorithm has no apparent improvement, but more calculation time in comparison method. While simulated annealing while for Glass/PP laminate and double coated steel plate with more elastic constants, Hybrid Genetic /Simulated Annealing algorithm is superior to the traditional simulated annealing method.