We synthesized novel side chain copolymers containing the stilbazolium tetraphenylborate for the linear electro-optic coefficient measurement. These polymers are very soluble in common organic solvents such as acetone, cyclohexanone, dimethylformamide etc. The second-order nonlinear optical properties of poly [1-[(N-ethylenepiperazyl)-stilbazolium tetraphenylborate]-N-[(1,1-dimethyl-m-isopropenyl)benzyl]carbamate-co-methylmethacrylate] (POLYMER Ia & Ib), poly [1-[(N-ethylenepiperazyl)-stilbazolium tetraphenyl borate]-N-[(1,1-dimethyl-m-isopropenyl)benzyl]carbamate-co-N-vinylcarbazole] (POLYMER II), and poly [1-[(N-ethylenepiperazyl)-stilbazolium tetraphenyl borate]-N-[(1,1-dimethyl-m-isopropenyl)benzyl]carbamate-co-4-hydroxyphenyl maleimide] (POLYMER III) were improved due to the change of the nonlinear optical chromophore in the side chain.