Aiming at the problem that the optical fiber temperature sensing device generally has a complicated structure and low sensitivity, an elliptical stomata temperature sensing device with high sensitivity is proposed and investigated in this paper. Temperature sensing is achieved based on surface plasmon and optical fiber temperature sensing technologies. It is mainly coated with a metal film on the outside of the fiber. The substance under test uses a mixture of chloroform and alcohol as a temperature-sensitive substance, which is simulated through the finite element vector software COMSOL. Simulation results show that when the incident wavelength is increased from 0.5 μm to 1.0 μm, the temperature measurement range is -20 ~120 ℃, the maximum spectral sensitivity is 6 nm/℃, the resolution is 1 337.12 RIU-1, and the measurement accuracy is 2.85×10-5 RIU.