Low-cost technologies with high energy density for effective storage of energy are highly desirable. AgCl has emerged as the most promising positive electrode material for seawater batteries, but is suffering from poor intrinsic electric conductivity and the low recovery after use which severely limit the application. Herein, three-dimensional high conductive structure of Ag/Carbon felts (CF) is embedded into AgCl substrate and an excellent performing AgCl/Ag/GF composite positive electrode is obtained. The cathodic polarizing curve showes that the current density of AgCl/Ag/CF electrode at a potential of −0.3 V vs SCE is 232.6 mA cm⁻². The AgCl/Ag/CF electrode delivers a very high initial discharge capacity about 179.0 mAh g⁻¹ at 100 mA g⁻¹ (95.8% of the theoretical capacity of AgCl) and 89.9% capacity retention after 3 cycles. The discharge/charge process and related structure are investigated. Further investigation of the mechanism demonstrates that 3D carbon felt and Ag layer coated play an important role in enhancing reaction kinetics and promoting the diffusion of Cl⁻ in the substrate.