In this paper, the power-consumption characteristics of a polymeric thermo-optic (TO) switch consisting of a silica under-cladding on silicon substrate, a polymer core surrounded with polymer upper-cladding, and aluminum heating electrodes with different widths were investigated. Norland optical adhesive 73 with a larger TO coefficient was selected as the core layer, which could reduce the power consumption effectively. The silica under-cladding, with large thermal conductivity, could shorten the response time. The influences of the heating electrode width and the air trench structure on the power consumption of the device were systemically studied. A device with different widths of electrodes was fabricated by using conventional semiconductor fabrication techniques and measured with the planar optical waveguide testing system. Under 1550-nm wavelength, the power consumption of the device would be reduced from 23.27 to 4.35 mW, while the heating electrode width was decreased from 25 to 7 μm. Furthermore, it would be reduced to 1.7 mW after the air trench structure was employed. The switching time of the device was also measured, which was about 200 μs.