By adopting polymer/silica hybrid rib waveguide structure,a low power -consumption Mach-Zehnder interferometer (MZI) thermo-optic switch is designed and fabricated with techniques including chemic al vapor deposition (CVD),spin-coating, wet-etching,etc.The wavelength dispersions of waveguide core,buffer and clad ding materials are measured,and output power and output spectrum are theoretically analyzed.Switching response and spectrum chara cteristics are measured using a tunable laser as input source.Under 1550nm wavelength,the driving power of the switch is about 7.8mW,the extinction ratio between ON state and OFF state is up to 32.6dB,and under the function of pure square-wave switching signal (peak-to-peak amplitude of 3V_pp),the rising time and falling time are 107μs and 71μs,respectively.Keeping applying the driv ing power at 1550nm wavelength on the device,the measured spectrum width is about 50nm (1520-1570nm) with an extinction ratio over 18dB.A noise-level-tunable driving source is developed with NE555and other integrate d circuits,and then the driving-noise-tolerance characteristics are investigated.Experimental results indicate that the allowed maximum noise-level is about 1.1Vpp with a requ i red extinction ratio larger than 10dB.The proposed results in this paper are of good meanings for practical applications of such thermo-op tic switches with the hybrid waveguide structure.