The change of temperature distributions and damping properties of rubber isolator are analyzed considering thermomechanical coupling process. Large strain constitutive model is introduced to describe non-linear deform and viscoelasticity simultaneously. The parameters of strain energy function are fitted by static tensile test of the material specimen. The time history curves of storage modulus and loss factor are tested by dynamic mechanical analysis (DMA). According to the DMA results the coefficients of Prony series are obtained by optimization. Assumed that the heat generation is equal to the energy produced by the inelastic deformation, thermomechanical coupled problem is computed by finite element method with proper mechanical boundary and heat convection boundary. The result shows that the heat built-up appears in the center of the model and the temperature declines from inside to outside. The simulated temperatures on the surface are close to the experiment. The stiffness and loss factor decline because of the inelastic effect. The initial dissipated energy obviously increases with the increase of frequency and decreases slowly with the temperature rising. The finial dissipated energy is insensitive to frequency and temperature, which is stable at different frequencies.