Particle　Swarm　Optimization　(PSO)　has　proved　to　be　an　effective　global　optimization　in　recent　years.　A　hybrid　particle　swarm　optimization　algorithm　combined　with　Extremal　Optimization　(HPSO-EO)　was　proposed　for　fixed-outline　floorplanning　in　this　paper.　A　string　structure　and　several　novel　updating　operations　for　HPSO-EO　are　adopted　respectively,　according　to　the　floorplan　problem.　We　have　carried　the　experiments　employed　the　MCNC　benchmarks　to　demonstrate　the　feasibility　of　HPSO-EO.　Simulation　results　are　shown　to　be　effective.　©　2011　IEEE.