Optical wavelength converter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) has been reported in this paper.Converted signal with continuous tunable wavelength is achieved by employing a tunable Erbium doped fiber ring laser.The influences of conversion wavelength spans,SOA small signal gain and input pump power on conversion efficiency are also investigated theoretically and experimentally.The results show that high SOA gain and large input pump power is contributive to the improvement of conversion efficiency.