A new azo-dye sy03 is introduced as photoalignment material of twist nematic liquid crystal (TN-LCD). sy03 is added into the mixture composed of polyimide SE-3310 and N,N-dimethylformamide for photoalingment of 90° TN-LCD. And the electro-optic perfermance of the cell aligned by it is measured, and then compared with that of the cell photoaligned with PI SE-3310 only. Apparently, the former is better than the latter for shorter raction time and lower threshold voltage with 98 ms reaction time and 1.7 V threshold voltage. Stability and contrast are improved, and the electrooptic response curve is sharper. After the cell is heated to 150 ℃, obvious change for its electro-optic performance does not occur, which proves its favorable thermal stability. By measuring the polarized UV absorption spectra, it is proved that the easy direction of liquid crystal director is perpendicular to the polarization direction of irradiation ultraviolet light.