A second-order nonlinear optical polymer was synthesized with bis-phenol-A as the polymer backbone, p-nitroaniline as the chromophore and cinnamyl group as the photo-sensitizer. The polymer films were obtained by spin-coating and poling by three methods respectively. These methods of poling include needle electrode corona poling, parallel wire electrode corona poling and contact poling, which were used to obtain the molecular orientation. The uniformity of the side-chain polymer films have been studied by external electro-optic measurement. The spatial resolution of system is 3 micrometers . Experimental results demonstrated that parallel wire electrode corona poling is easier to obtained large poled area with good uniformity than that of other methods.