The calorescence coefficients of silicon resin reached -3.6×10-4 /℃ at 650 nm, and -3.3×0-4 /℃ at 632.8 nm which were tested by V prism device. A silicon resin waveguide is formed on a quartz substrate and its effective refractive indexes N at different temperatures are detected by coupled prism method. The thickness h and refractive index n1 of the film at different temperatures are calculated and these results show that the variety of N comes from the n1 and the reflection angle of guided wave on the boundary. The experimental results of waveguide reveal that the larger calorescence coefficients of silicon resin are induced by the larger orientational polarizability of the molecules in the material and it can be useful in making the thermo-optic switch of low power dissipation in short-range networks.