A nonliquid crystal polymer was prepared by introducing the azobenzene group into the main chain of the poly(amic acid). The polymer film can be easily prepared by a general method. The obtained film exhibits a high bending intensity and shows fast bending response and a very large bending angle (reach of 90 degrees) at room temperature without temperature heating, which can improve the efficiency of the transformation of energy from light to mechanical energy. The surface structure of the relief grating also was investigated by atomic force microscopy. The depth of typical surface relief was approximately 65 nm. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1330-1334, 2009