A temperature sensor by using an alcohol-filled side-hole fiber (SHF) based Sagnac interferometer is proposed and experimentally demonstrated. SHF is a highly birefringent fiber, which has two air holes running aside the core in the cladding of the fiber. Temperature changes the refractive index of the alcohol liquid filled in the air holes of the SHF, leading to the variation in birefringence of the SHF and hence interference pattern shift of the Sagnac interferometer. A sensitivity of 86.8 pm/℃ is achieved when temperature changes between 20 ℃ and 80 ℃. It is about eight times of that of a normal fiber Bragg grating (FBG) sensor.