Cross-linked azobenzene containing copolymer is synthesized and utilized to fabricate axially-symmetric phase retardation plate.Based on the photo-isomerization characteristics of azobenzene copolymer,a linearly polarized light inducing device is set up.Placed on a rotating stage,an azobenzene film is irradiated by a linearly polarized light to form molecule alignment with axially-symmetric distribution.The probe beam is used to detect in real time the phase retardation ofthe film under the effect of linearly polarized light.During the investigation,a particular software on the computer is used to record the intensity curve of the probe light which goes through the film placed in the group of orthogonal polarizer plate.After that,a measuring optical circuit is set up to measure the axial symmetry of the phase retardation plate and the measurement patterns are recorded with a CCD.The experimental results show that the induced birefringence is 0.0205,the thickness is 3 μm,and the phase retardation is 65°.