An amorphous polymer containing azo-side groups has been investigated regarding to the photoinduced anisotropy and polarization holographic recording. Measurements reveal that the effect of photobleaching process should be taken into account in explaining the experimental results in the azobenzene side-chain polymer film and that the polymer possesses large magnitude of photoinduced birefringence (Δn=7.8×10-3). A reversible polarization hologram with high efficiency (19.3%) is recorded with a CW 532 nm laser in this thin film.