We　demonstrated　an　ultra-low　noise　polarization-maintaining　(PM)　single　frequency　fiber　laser　(SFFL)　at　2　mu　m.　By　suppressing　the　pump　relative　intensity　noise　using　a　feedback　loop　control,　the　RIN　and　frequency　noise　of　the　SFFL　are　simultaneously　reduced,　and　the　reduction　is　about　3　-　15　dB　and　3　-　8.4　dB,　respectively.　After　two　stage　Tm3+-doped　PM　fiber　amplifier,　the　output　power　reached　about　5.2　W.　Meanwhile,　the　frequency　noise　almost　has　no　increases,　which　is　still　below　100　Hz/root　Hz　after　13　Hz.　And　the　frequency-tunable　range　is　approximately　2　GHz　with　frequency　response　of　46　MHz/V.