Floorplanning　is　a　critical　step　in　the　physical　design　of　Very　Large　Scale　Integrated　(VLSI)　circuits.　Its　main　target　is　optimizing　the　layout　area　and　interconnection　wire　length　of　chips,　which　can　be　transformed　into　a　Multi-objective　Optimization　Problem　(MOP).　In　this　paper,　we　propose　a　discrete　Particle　Swarm　Optimization　(PSO)　algorithm　for　MOP　which　could　take　many　key　objectives　into　consideration　and　give　a　good　compromise　between　them.　The　experiments　on　MCNC　benchmarks　show　that　the　proposed　algorithm　is　effective,　and　gives　out　many　optional　results　for　user＇s　choice　according　to　partialness,　which　can　not　be　finished　by　traditional　methods.　©　Springer-Verlag　2009.