Electrochemical reduction has been regarded as a sustainable strategy to tackle energy-intensive operations by the Haber-Bosch process achieving catalytic conversion of N-2 to NH3 under mild conditions. However, the challenge of N-2 electroconversion emphasizes the requirement of efficient electrocatalysts. In this paper, we report the development of porous bromide-derived Ag film (BD-Ag/AF) as an efficient electrocatalyst for N-2 reduction reaction. During electrochemical test, Br- anions are released and adsorbed onto the surfaces of the electrode, suppressing hydrogen evolution reaction. Such BD-Ag/AF shows a high Faradaic efficiency of 7.36% at -0.6 V vs reversible hydrogen electrode in 0.1 M Na2SO4, which is higher than that (0.38%) of porous Ag film without Br- anions. Moreover, it exhibits excellent long-term electrochemical durability.