Seawater temperature is one of the basic parameters of ocean dynamics and it plays a key role in the interaction between the ocean and atmosphere. What′s more, seawater temperature is the most important parameter of all marine phenomenon research. In order to achieve the simultaneously measurement of seawater temperature at two points, a theoretical model of Sagnac ring with two high birefringence elliptical fibers is constructed. The transmission spectrum of the theoretical model is obtained by Jones matrix equation, and the relationship between the transmission spectra and the various parts of the structure parameters is also obtained. By the numerical simulation of the theoretical model with Matlab software, the impact of the transmission spectra is studied on the changes of two high birefringence elliptical fibers length proportion, deflection angle and temperature. The results show that the optimum length ratio of two high birefringence elliptical fibers is 1∶2. The polarization angles of the polarization controllers should be π/6 and π/3, respectively. The transmission spectra shift to shorter wavelength when the temperature increases. The formula is obtained to calculate the temperature changes of two high birefringence elliptical fibers by the wavelength shifts of spectral peaks. In addition, the length of single-mode fiber between the two high birefringence elliptical fibers has no effect on the shape of transmission spectrum and temperature sensitivity. The model can theoretically support and guide the practical application of high birefringence fiber Sagnac ring temperature sensor.