The second order Loyt-Sagnac interferometer was constructed by inserting two sections of highly birefringence fibers into the fiber loop and adjusting the fusion splicing angle. The transmission spectrum of the highly birefringence fiber Sagnac interferometer was calculated by using the Jones matrix analysis. The polarization angle of input light and the lengths of highly birefringence fibers were optimized. These two kinds of temperature sensors were simulated and experimented. The Simulation results show that the temperature sensitivity of the second order Loyt-Sagnac configuration can be enhanced because of its Vernier effect. The experimental results show that the temperature sensitivity is increased from －1.46 nm/℃ to －17.99 nm/℃ by using the proposed structure, increased 12.32 times.