A novel and simple refractive index in sensitive temperature sensor,which consists of 45°-tilted long period fiber gr ating (LPFG) pair inscribed in PANDA polarization-maintaining fiber (PMF) by using focused high-frequency CO_2las er,is proposed in this paper. The mechanism of refractive index insensitivity originates from the destructive theory of grating effect and birefringence effect of polarization maintaining.Experiment al results indicate that the peaks with different temperature sensitivities linearly shift towards longer wavelength with temperature.The maximum temperature sensitivity reach es up to 37pm/℃, which is larger than that acquired by cascading two special long-period fiber g ratings with rotary refractive index modulation (30pm/℃),and is 3times larger than that acquired by using un-tilted Bragg fiber gratings (about 10pm/℃). What′s more,the proposed sensor is insensitive to ambient refractive index wh en specific conditions are matched.Such a sensor is more suitable for liquid temperature measurement without considering cross sensitivity in actual industri al production.