A two-channel fiber optic sensor based on surface plasmon resonance was developed. The effects of two materials of Au and Cu on the performances of the fiber optic sensor modulated by incident wavelength were analyzed. The thickness of metal was optimized, and the optimized thickness of the metal dAu=47 nm and dCu=53 nm was chosen to carry out numerical simulation. And the results show that, the sensitivity of the channel of Au is higher than the sensitivity of the channel of Cu, on the other hand, the detection precision of the channel of Cu is four times higher than the detection precision of the channel of Au. The sensing channel of Au is suitable for the detection of the lower refractive index of sensing medium, and the sensing channel of Cu is suitable for the detection of higher refractive index of sensing medium. The proposed sensor has expanded the detection range, compared with the single channel sensor. The detection accuracy of the two-channel SPR fiber sensor is higher than that of the single channel sensor. The measuring sensitivities of two-channel SPR fiber sensor and conventional single channel sensor are the same.