Abstract: The evolutionary structural optimization method has beenunder continuous development since 1992. Recently abi-direction evolutionary structural optimization method is developed whereby materialcan be added and removed. In order to consider the effects of elementremoving or adding on structural stress constraints, in this paper, a newbi-direction evolutionary structural optimization method is proposed forstructures under multiple loads. First, based on an idea that artificialmaterial is added around optimal structural cavities and boundaries, astructural optimization model and a set of stress sensitivity formula arebuilt. Then combining structural stresses and its sensitivities, a set ofcriteria, for adding and removing finite elements for the topologyoptimization problem of structures under multiple loads, is established, and a kindof new topology optimization procedure is obtained. Several simulationexamples show that the proposed method is valid and effective forstructural topology optimization.