A microstructured-fiber containing six large air holes is proposed to achieve surface plasmon resonance (SPR) sensor. The finite element method is used to analyze characteristics of the SPR sensor. The effects of the thickness of metal films, pitch between air holes, diameter of air holes and refractive index of liquid on the resonance wavelength are elucidated. The sensitivity of sensor is also given. The result shows that the resonance wavelength is sensitive to the thickness of metal film and refractive index of environment, while the resonance wavelength does not change basically when the pitch between air holes and diameter of air holes varies. The proposed SPR sensor exhibits high sensitivity up to 10-4.