The　dynamic　topology　optimization　of　three-dimensional　continuum　structures　subject　to　frequency　constraints　is　investigated　using　Independent　Continuous　Mapping　(ICM)　design　variable　fields.　The　composite　exponential　function　(CEF)　is　selected　to　be　a　filter　function　which　recognizes　the　design　variables　and　to　implement　the　changing　process　of　design　variables　from　＂discrete＂　to　＂continuous＂　and　back　to　＂discrete.＂　Explicit　formulations　of　frequency　constraints　are　given　based　on　filter　functions,　first-order　Taylor　series　expansion.　And　an　improved　optimal　model　is　formulated　using　CEF　and　the　explicit　frequency　constraints.　Dual　sequential　quadratic　programming　(DSQP)　algorithm　is　used　to　solve　the　optimal　model.　The　program　is　developed　on　the　platform　of　MSC　Patran　&　Nastran.　Finally,　numerical　examples　are　given　to　demonstrate　the　validity　and　applicability　of　the　proposed　method.