A temperature self-compensating strain sensor is demonstrated by fill ing specific material with negative temperature coefficient of refractive index in the cladding air holes o f hexagonal photonic crystal fiber Bragg grating (PCFBG).Based on coupled mode theory,we establish theore tical analysis model. And then,combined with control variable method,we make an numerical analysis a bout the change of effective refractive index in different temperatures and wavelengths.Through ins erting different liquid materials in the cladding air holes,we find that the resonance wavelength of fu ndamental mode or the first-order optical mode cannot be sensitive to the temperature.On the basis o f that,we study temperature and strain sensitivity sensing properties of different modes in PCFB G.The experimental results show that when the environment temperature is increased fro m －20℃ to 100℃,the reflection spectra of fundamental mode drift 2.3pm and the sensitivity of strain is up to 1.2348pm/με when filling material I in the cladding air h oles;those of the first-order mode drift 4.6pm and the sensitivity of strain is up to 1.3118pm/με when filling material II in the cladding air holes.As a result,it can achieve temperature insensitive strain measurement when to specific material with negative temperatu re coefficients refractive index is filled in the cladding air holes of photonic crystal fiber.