AbstractSide‐chain azobenzene‐containing liquid crystalline polymer (ALCP) of Poly(6‐[4‐(4‐cyanophenylazo)phenoxy] x‐methylene methacrylate)(Px, x is 2 or 6) was synthesized and used to study its photoinduced alignment behavior irradiated by a linearly polarized laser at room temperature. The relationships between transmittance and irradiation time as well as transmittance and various incident angles were studied in detail. The oversaturation phenomenon of P2 film was found to be higher than 1 mW/cm2 under irradiation energy density. A model of the biaxial orientation was introduced to explain the phenomenon: it is the rigid short spacer that makes it possible for mesogen to coexist in a way of out‐of‐plane and in‐plane orientation (biaxial orientation), in which the type of photoinduced motions is a single mesogen motion in the film of P2, whereas in the film of P6 with longer spacer, the motion is a microdomain motion. The whole domain motion restricted the out‐of‐plane orientation, which shows a slow orientation rate and all mesogens aligned within the film plane. A novel dynamic fitting was also presented to describe the orientation of P2, which was discussed in terms of the fitting parameters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1378–1384, 2006