Based　on　the　Independent　Continuous　Mapping　method　(ICM),　a　topological　optimization　model　with　continuous　topological　variables　is　built　by　introducing　three　filter　functions　for　element　weight,　element　allowable　stress　and　element　stiffness,　which　transform　the　0-1　type　discrete　topological　variables　into　continuous　topological　variables　between　0　and　1.　Two　methods　for　the　filter　functions　are　adopted　to　avoid　the　structural　singularity　and　recover　falsely　deleted　elements:　the　weak　material　element　method　and　the　tiny　section　element　method.　Three　criteria　(no　structural　singularity,　no　violated　constraints　and　no　change　of　structural　weight)　are　introduced　to　judge　iteration　convergence.　These　criteria　allow　finding　an　appropriate　threshold　by　adjusting　a　discount　factor　in　the　iteration　procedure.　To　improve　the　efficiency,　the　original　optimization　model　is　transformed　into　a　dual　problem　according　to　the　dual　theory　and　solved　in　its　dual　space.　By　using　MSC/Nastran　as　the　structural　solver　and　MSC/Patran　as　the　developing　platform,　a　topological　optimization　software　of　frame　structures　is　accomplished.　Numerical　examples　show　that　the　ICM　method　is　very　efficient　for　the　topological　optimization　of　frame　structures.