By utilizing the opposite thermo-optic characteristics of silicon oxynitride and polymer materials,a hybrid integrated silicon oxynitride and polymer channel waveguide based variable optical attenuator with low power was proposed,which consisted of a polymer core and a silicon oxynitride cladding.A heater is deposited on the S-bend waveguide to form an active region so as to realize tunable optical power attenuation by utilizing thermo-optic effect.Theoretical results show that an optical attenuation of ~50 dB can be achieved with an applied electrical power of 3.6 mW.Experimental result shows an attenuation of 0~40 dB,correspondingly,a maximum temperature change of 70.4℃ ,and an insertion loss of 5.4 dB.