In　this　paper,　we　analyze　the　relativistic　Thomson　scattering　with　few-cycle　laser　pulses.　We　conclude　that　scattering　of　high　energy　electrons　with　mono-cycle　laser　pulses　is　capable　of　producing　attosecond　pulses.　The　calculation　shows　that　with　a　1.5　cycle　pulse　at　the　wavelength　of　I　mu　m,　the　normalized　electric　field　intensity　of　0.　01,　and　the　electron　relativistic　factor　of　50,　Xray　pulses　of　0.2　as　can　be　obtained.　We　also　discussed　the　influence　of　the　carrier-envelop　phase　offset　and　the　initial　phase　phi(in)　of　electrons　starting　to　interact　with　the　optical　field　on　the　radiation　spectrum.　The　calculation　results　demo　nstrate　that　proper　values　of　phase　can　result　in　single　attosecond　pulse　generation,　as　well　as　the　possibility　of　frequency　tuning.