Abstract: Aiming at the existing problems in genetic algorithm and evolutionary strategy calculation, the authors apply the evolutionary-simplex algorithm based on floating encoding to the inverse analysis of structural physical parameters under the dynamic response conditions, and establish an inverse analysis method about structural physical parameter based on incomplete modal parameters. As compared with other inverse analysis methods, this method shows a series of advantages such as high precision and searching efficiency, no dependence on the selection of initial values, and sufficient reflection on the inadequate high rank modal information.