A comprehensive broad-band model of orthogonal dual-pump four-wave mixing (FWM) in semiconductor optical amplifier (SOA) is presented in the case of the polarization state of the input signal being arbitrary. By performing numerical simulation and taking the all-optical wavelength conversion based on orthogonal dual-pump FWM in an SOA for example, the effects of the input light powers, frequency detuning and polarization state of the input signal on the orthogonal dual-pump FWM and the performances of wavelength conversion are theoretically investigated.