The design of fluorescent probe to detect Zn(II) ion high sensitively and operational simply has been attracted much attention recently. In this study, 2, 4-diamino-2'-carboxyl azobenzene (L1) was synthesized and characterized by NMR, IR spectra. The UV absorption spectra of L1 with Zn(II) ion changed with an isosbestic point at 356 nm. When L1 reacted with ZnSO₄, the distinct colour of L1 changed from yellow to orange. In the solution of L1 and ZnSO₄, a marked enhanced fluorescene enhancement was observed at 484 nm (λex = 330 nm) and emitted cyan fluorescence under UV light. Furthermore, L1 reacted with zinc gluconate solution, which makes L1 can be serves as the applied material to test Zn(II) ion in zinc supplement.