A poly(bromophenol-blue)-graphene(PBPB-GO) composite film modified glassy carbon electrode(GCE) was fabricated through a simple and controllable dropping and in situ electro polymerizing method，which was denoted as a DA electrochemical sensor.The result indicated that PBPB-GO composite film had a good catalytic effect on the electrochemical reduction of DA.The conductivities of bare GCE，GO/GCE，PBPB/GCE and PBPB/GO/GCE film were characterized through electrochemical impedance spectroscopy.The comparison results showed that the PBPB/GO/GCE had a lower resistance.Moreover，scanning electron microscopy was used to characterize the surface morphology of bare GO，GO/GCE and PBPB/GO/GCE，and the results indicated that PBPB-GO film had a loose and porous structure，which was beneficial to the enrichment of DA.Furthermore，the electrochemical reaction mechanism of DA on the PBPB/GO/GCE was studied and the results indicated that the electrochemical reaction of DA on the PBPB/GO/GCE was an adsorption controlled and proton participating process.The detection conditions were optimized，and the optimal electro polymerization cycles number was 15，the optimal quantity of GO(2 mg/mL) was 2 μL , and the optimal electrolyte solution was 0.1 mol/L phosphate buffer solution(pH 6.0).Under the optimal detection conditions，a wide linear range over DA concentration of 5.0×10-8-2.0×10-4 mol/L was obtained with a low detection limit of 1.0×10-8 mol/L.The DA electrochemical sensor showed good stability and reproducibility，high sensitivity and good selectivity，and was successfully applied in the detection of DA in dopamine injection.