Floorplanning　is　a　key　step　in　the　physical　design　of　Very　Large　Scale　Integrated　(VLSI)　circuits.　It　is　a　multi-objective　combinatorial　optimization　and　has　been　proved　to　be　a　NP-hard　problem.　To　solve　this　problem,　a　coevolutionary　multi-objective　particle　swarm　optimization　(CMOPSO)　algorithm　is　proposed　in　this　paper.　The　algorithm　imports　the　concept　of　coevolutionary　algorithm　and　elitist　strategy　into　basic　PSO　algorithm,　takes　both　the　layout　area　and　total　interconnection　wire　length　into　consideration　simultaneously.　Experimental　results　showed　the　new　algorithm　can　achieve　a　better　performance.　©　2012　IEEE.