This　paper　is　concerned　with　the　free　vibration　of　a　rotating　tapered　Timoshenko　beam　with　preset　and　pre-twist　angles.　The　power　series　method　is　used　to　obtain　the　frequencies　and　complex　modes　of　the　structure.　The　rotating　velocity　related　terms　are　re-classified　into　three　types,　namely,　static　centrifugal　terms,　dynamic　centrifugal　terms　and　the　gyroscopic　terms.　This　reclassification　provides　clearer　descriptions　of　the　varying　frequencies　with　respect　to　the　rotating　velocity.　The　gyroscopic　coupling　among　different　directions　are　discussed.　The　overall　contour　of　the　complex　modal　vibrations　is　recorded　and　investigated　by　time　series　snapshots　of　neutral　line　motions　and　tip　end　cross-section　motions.