We　propose　a　scheme　for　generating　macroscopic　quantum-interference　(Schrodinger-cat)　states　of　the　motion　of　a　trapped　ion.　In　the　scheme,　a　trapped　ion　is　driven　by　two　laser　beams　tuned　to　the　first　lower　and　upper　vibrational　sidebands,　respectively.　Under　certain　conditions,　the　detection　of　the　internal　state　of　the　ion　leaves　the　vibrational　motion　in　a　coherent　state　superposition.　The　scheme　can　be　easily　generalized　to　prepare　other　kinds　of　cat　states.