Alkaline seawater electrolysis faces serious problems such as low catalytic activity of bifunctional catalysts and vulnerability to Cl- corrosion. Hence, Ru-doped nickel phosphide asymmetric structure (Ru-Ni2P/Ni5P4) has been synthesized as highly efficient and corrosion resistant electrocatalysts for alkaline seawater electrolysis at high current density. In-situ characterization technique and DFT calculations reveal that compared with the monophase nickel phosphide, the construction of NixP asymmetric structure manipulate the electronic structure and d-band center, promoting the adsorption of intermediates, as well as accelerate phase transition of the OER process. Moreover, the weak adsorption energy of Cl- on the surface of the Ru-Ni2P/Ni5P4 catalyst avoids the corrosion of Cl- in seawater. Consequently, Ru-Ni2P/Ni5P4 achieve 1000 mA cm−2 with overpotentials of only 128 and 450 mV for HER and OER, respectively. After assembling the Anion-exchange-membrane water electrolyzer (AEMWE), Ru-Ni2P/Ni5P4 shows high average efficiency and economic value at different current densities, and demonstrates its corrosion resistance to Cl- and potential for industrial applications.