Abstract: A modified harmony search (MHS) algorithm was proposed to solve structural design problem. A novel position updating operator was applied to enhance the development capability of solution space. Equivalent differential strategy was used to adaptively adjust harmony distance bandwidth， which could improve the searching accuracy and escape the local optima. To confirm the MHS effectiveness， three structural design optimization problems were tested. The tests demonstrated that MHS had better result than that of other four harmony search algorithms. Comparing with the best solution reported in recent literature， the MHS could find out better solutions to the optimization problem of structural design.

Key words: MHS, structural design, position updating, equivalent differential, effectiveness