Abstract: The dynamic response of functionally graded plates was simulated under impulsive load. These platesare supposed to be metal mat rix composites (MMC) made f rom aluminum alloy reinforced by ceramic particles. Thereinforcement volume f raction varies continuously along thickness following a power law. The reinforcement volumef raction reaches it s maximum at both f ront surface and back surface with the symmet ric dist ribution. The result sshow that the st ress wave propagations in such gradient st ructures are very complex. The elastic and viscoplasticwaves are coupled together and the amplitude of reflected tension wave and the unloading wave have very close relation with the gradient dist ribution of the composition. The dist ributions of equivalent plastic st rain , dissipated , kinetic and elastic st rain energies are all dependent on the gradient dist ribution of the composition. All these play avery important role in optimum design of the functionally graded st ructures under the impact load.