In　addition　to　wirelength　and　area,　modern　floorplans　need　to　consider　various　constraints　such　as　fixed-outline.　To　handle　the　fixed-outline　floorplanning　optimization　problem　efficiently,　we　propose　an　improved　simulated　annealing　(SA)　algorithm,　which　optimizes　the　area,　the　total　wirelength,　and　the　prescribed　outline　constraints　at　the　same　time.　In　order　to　enhance　the　effectiveness　of　SA　algorithm,　we　propose　a　novel　feasible　solution　strategy　which　ensures　that　viable　solution　would　be　found　at　all　times.　Moreover,　we　propose　a　new　penalty　function　to　better　solve　the　prescribed　outline　constraint.　It　consists　of　a　violation　area　function　to　prevent　modules　from　moving　to　the　prescribed　outline,　and　an　excessive　violation　function　to　enable　the　modules　to　move　close　to　the　optimal　positions.　Experimental　results　show　that　the　proposed　algorithm　is　effective　and　efficient　to　obtain　a　fixed-outline　floorplan,　and　achieves　a　100%　success　rate　on　each　benchmark　in　different　aspect　ratios.