The study focuses on the development of an efficient and cost-effective stainless steel-based bifunctional water electrolysis catalyst, named Ru-PSS, for green hydrogen production. This catalyst was designed using inexpensive 316L stainless steel and utilized a coupling interface and doping strategy to enhance its performance. Experimental results demonstrated that the Ru-PSS electrode significantly reduced overpotentials for both the hydrogen evolution reaction (248 mV) and the oxygen evolution reaction (353 mV) at a current density of 500 mA∙cm-2. The electrode, when incorporated in a symmetrical anion exchange membrane electrolyser, achieved an industrial high current density of 500 mA∙cm-2 at a low voltage of 1.82 V, showcasing its efficiency and cost-effectiveness. The study further explored the catalytic mechanisms involved in the electrode, including adsorption evolution and oxide pathway mechanisms. Through material characterization and density-functional theory calculations, the researchers identified the formation of heterostructures (FeP4/Ni2P) on the stainless steel surface, providing abundant active sites for catalytic reactions. Additionally, trace Ru doping (Ru-FeP4/Ni2P) improved the catalyst's performance by optimizing the free energy of hydrogen adsorption and activating a more catalytically active reaction mechanism. The findings suggest that utilizing stainless steel as a catalyst material can lead to highly efficient and stable catalysts for water electrolysis, contributing to the development of green hydrogen production technologies and promoting sustainable energy practices.