A Long-Period Fiber Grating (LPFG) fabricated by CO2 laser in a symmetrical two-hole single-mode fiber (STHSMF) for refraction index (RI) measurement is demonstrated. The solved sugar liquid of different concentration was filled into the holes by capillary force and its RI was experimentally measured. The results show that resonant peak shifts toward shorter wavelengths with its resonance peak intensity changes a little when the external refractive index increases. RI sensitivity of 141.67 nm/RIU have been achieved with R2 of 0.975.The temperature sensitivity of the STHSMF is also investigated.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.