In this paper, a simple and efficient method, genetic algorithm (GA), for synthesis metamaterials is proposed to develop high absorption, wideband and multi-band absorbers. Several steps are added to the GA to higher its efficiency. We present three representative examples, for both single-layer and multilayer, with different reflectivity objectives which are optimized successfully by the GA. This GA based design is illustrated to be applicable and multifunctional in the metamaterials synthesis designs.