A microstructured fiber based surface plasmon sensor with a high sensitivity of 2.4×10-6 was proposed using an central analyte-filled channel in the core region. Through the analyte modulation, the variation trend of the resonance loss with the analyte refractive index was demonstrated to be contrary to that of the sensitivity. In this way significantly enhancement in the detection accurary can be achieved. The resolution of the sensor was also improved by properly choosing the size of the central hole. With analyte infiltration into the core, the calibration curve of the sensor can be effectively linearized, partially alleviating the difficulty in data processing.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.