Abstract: In VLSI floorplanning,different modules have different areas and longer edges.Based on this fact,this paper presents the concept of weight of each module and the corresponding floorplanning algorithm.In this algorithm,with the decreasing of temperature in the annealing process,different modules are selected with different possibilities based on the ir weights.The algorithm overcomes the demerit that different modules are selected with the same possibility in the optimization process.Experimental results show that this algorithm improves the quality of floorplanning result.