The work aims to study the effect of various preparation technologies on properties of electrode so as to improve the conductivity and discharge property of positive electrode of polyaniline seawater battery. The polyaniline (PANI)/manganese dioxide (MnO2)/graphene oxide (GO) composite electrode was synthesized by electrochemical method on graphite paper and the optimum synthesis condition of the composite electrode was studied. The XRD, SEM and FT-IR were used to characterize the composite electrode. The electrochemical property of the composite electrode was measured by the AC impedance method, cyclic voltammetry and polarization curve. After the graphite paper was oxidized at room temperature for 60 minutes under the oxidation current density of 30 mA/cm2, the optimal PMGO composite electrode was synthesized at the polymerization current density of 18 mA/cm2 in HClO4-aniline solution containing sulfosalicylic acid (SSA) of 15 g/Land 0.2 mol/L MnSO4 for 20 minutes of polymerization. The seawater battery composed of composite electrode and magnesium alloy discharged to 1 V at a constant current of 200 mA/g, and the specific energy reached 600 W?h/kg. The surface microstructure of the PMGO composite electrode showed a complex 3D network structure constructed by nanowires on graphite paper. Polyaniline and manganese dioxide were successfully compounded on the surface of graphene oxide. The conductivity of polyaniline doped with perchloric acid has been enhanced. A large amount of GO is formed on the surface of graphite paper by oxidation, providing numerous active sites for the polymerization of PANI. Thus, specific surface area of electrode prepared increases and fully contacts electrolyte, which improves the utilization of active material and reduces the composite electrode polarization. The electrochemical property of PMGO is much better than that of AgCl electrode.