Abstract: The layout optimization, which involves size, shape and topology optimization, is the most difficult task in structural optimization. An alternative approach of structural layout optimization based on more ground structures for trusses is presented. A single ground structure is substituted by various reasonable ground structures which are generated intellectively. The optimum design is obtained in the results of topology optimization of different ground structures. The limitation of missing the optimal solution due to confining the solving space by traditional ground structure method is overcome. The shape and topology optimization is separated and the difficulty of solving layout optimization problem is reduced. Combining with topology variation method, an intelligent design process including collocation, generation, analysis and optimization of trusses can be completed. Examples show the proposed technique of layout optimization for trusses is effective and reliable.