Abstract: Poly-p-aminobenzene sulfonic acid modified electrode was prepared by electrochemical polymerization of p-aminobenzene sulfonic acid on the surface of glassy carbon electrode, and electrochemical behavior of this modified electrode was studied by cyclic voltammetry and differential pulse voltammetry. It was found that in PBS of pH 7.00, a sensitive oxidation peak of tyrosine was observed at 0.478 V. Linear relationship between values of peak current and concentration of tyrosine was kept in the range of 1.0×10-7-6.0×10-5mol·L-1, with detection limit (3S/N) of 2.0×10-8mol·L-1. The proposed method was applied to the determination of tyrosine in urine, giving values of recovery in the range of 91.5%-106.0%.