The fabrication and characteristics of a polymeric electro-optic modulator with double channels in attenuated total reflection (ATR) configuration, made of a thermally crosslinkable polyurethane, has been investigated. The fabrication procedure of proposed double-channel ATR modulator is extremely simple, it can be implemented by replacing a single electrode with two discrete electrodes in a single channel ATR modulator. Working at 832 nm, a double polarization modulator is demonstrated with the electro-optical coefficient of 24.2 Pm/V, an independent operation modulation speed of 500 MHz and low insertion losses of below 1.5 dB by measuring polarization modulation of the poled devices. There is no measurable cross talks due to the large horizontal separation of two channels and the small vertical separation of the electrode pair. A long-term thermal stability of the fabrication modulator at an elevated temperature, 100 ℃, is obtained due to cross-linking polyurethane as the waveguide layer of the devices.