An optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers was designed and fabricated to realize high-sensitivity temperature sensing. In the optical fiber Sagnac loop, two sections of polarization maintaining fibers were spliced with an intersection angle of 45° between their fast axes. The interference spectrum formula of the Sagnac interference loop by the Jones matrix was deduced theoretically. The influence of main parameters of the formula on the output characteristics of the Sagnac interference loop was studied in simulation. The simulation results show that vernier effect can be achieved in the optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers, of which the average length and the length difference affect wavelength intervals and envelope periods of output interference spectra of the Sagnac interference loop, respectively. In addition, the optical fiber Sagnac interference loop with two angle shift spliced polarization maintaining fibers was applied as a fiber temperature sensor experimentally. The results show that the sensitivity of the proposed temperature sensor based on Sagnac interference loop is -2.44 nm/℃ within 2 cm temperature zone, which is 14.97 times as compared with that (-0.163 nm/℃) of ordinary Sagnac loop sensors without vernier effect.