Based on the configuration of surface plasmon resonance (SPR) sensor, the SPR sensor model is set up, and the thermo-properties of various parts in the model are discussed. The thermo-characteristics of SPR spectra in wavelength interrogation and angular interrogation are investigated. Results show that thermo-optic and dispersion effects in the model deteriorate the sensitivity of SPR sensor, especially the thermo-optic effects. Mathematical expression is established to describe the resonance wavelength or angle, which is dependent of temperature. It demonstrates that the thermo-property of sensing medium excites the fluctuation of resonance wavelength or angle more intensely than that of the substrate or metal film in 1–2 orders. Our theoretical research is consistent with the previous experimental results.