We report the fabrication of long-period gratings (LPGs) in elliptical microfibers with femtosecond laser.Based on the numerical analysis of the modes and the mode coupling condition of elliptical microfibers,an LPG is fabricated with a very short pitch of 10 μm by periodically modifying the fiber surface,which demonstrates very strong polarization-dependent resonances,a very low temperature sensitivity of a few picometers in air,and high temperature sensitivity of-1.62 nm/℃ in refractive index oil.