Robotic　Friction　Stir　Welding　(RFSW)　technology　integrates　the　advantages　of　friction　stir　welding　and　industrial　robots,　finding　extensive　applications　and　research　in　aerospace,　shipbuilding,　and　new　energy　vehicles.　However,　the　high-speed　rotational　process　of　friction　stir　welding　combined　with　the　low　stiffness　characteristics　of　serial　industrial　robots　inevitably　introduces　vibrations　during　the　welding　process.　This　paper　investigates　the　vibration　patterns　and　impacts　during　the　RFSW　process　and　proposes　an　active　vibration　avoidance　control　method　for　variable　speed　welding　based　on　constant　heat　input.　This　method　utilizes　a　vibration　feedback　strategy　that　adjusts　the　spindle　speed　actively　if　the　end-effector＇s　vibration　exceeds　a　threshold,　thereby　avoiding　the　modal　frequencies　of　the　robot　at　its　current　pose.　Concurrently,　it　calculates　and　adjusts　the　welding　speed　of　the　robot　according　to　the　thermal　equilibrium　equation　to　maintain　constant　heat　input.　A　simplified　dynamic　model　of　the　RFSW　robot　was　established,　and　the　feasibility　of　this　method　was　validated　through　simulation　experiments.　This　study　fills　the　gap　in　vibration　analysis　of　RFSW　and　provides　new　insights　into　control　strategies　and　process　optimization　for　robotic　friction　stir　welding.