We propose and experimentally demonstrate a 2×2 thermo-optic(TO) crossbar switch implemented by dual photonic crystal nanobeam(PCN)cavities within a silicon-on-insulator(SOI)platform.By thermally tuning the refractive index of silicon,the resonance wavelength of the PCN cavities can be red-shifted.With the help of the ultrasmall mode volumes of the PCN cavities,only～0.16 mW power is needed to change the switching state.With a spectral passband of 0.09 nm at the 1583.75 nm operation wavelength,the insertion loss(IL)and crosstalk(CT)performances were measured as IL(bar)=-0.2 dB,CT(bar)=-15 dB,IL(cross)=-1.5 dB,and CT(cross)=-15 dB.Furthermore,the thermal tuning efficiency of the fabricated device is as high as1.23 nm/mW. We propose and experimentally demonstrate a 2 × 2 thermo-optic (TO) crossbar switch implemented by dual photonic crystal nanobeam (PCN) cavities within a silicon-on-insulator (SOI) platform.By thermally tuning the refractive index of silicon, the resonance Wavelength of the PCN cavities can be red-shifted. With the help of the ultrasmall mode volumes of the PCN cavities, only ~ 0.16 mW power is needed to change the switching state. W a a spectral passband of 0.09 nm at the 1583.75 nm operating wavelengths , the insertion loss (IL) and crosstalk (CT) performances were measured as IL (bar) = -0.2 dB, CT (bar) = - 15 dB, 15 dB. Thermal Co., the thermal tuning efficiency of the fabricated device is as high as 1.23 nm / mW.