To enhance the efficient and rate of magnesium/seawater reaction, Mg-based hydro-reactive materials were prepared via a multiple variable speed cycle process by high-energy milling method in inert atmosphere. Scanning electron microscope (SEM), thermogravimetry (TG) and specific surface test were used to characterize the microstructure and oxidation characteristic of the materials. The real-time amount of hydrogen produced by reaction of Mg-based materials and seawater was recorded using an independent designed metal/water reaction device. The hydro-reactivity of Mg-based hydro-reactive metal materials was studied. Results show that the high-energy milling can significantly enhance the reaction activity of Mg-based materials and seawater. The reaction efficiency of magnesium powder after ball mill reaches 80.5%. Addition of catalyst in the process of ball mill can further enhance the reaction activity of Mg-based hydro-reactive materials. The total yield of reaction can reach 91.1%. The hydrogen generation reaction rate in the fast stage is 741 mL·min^-1·g^-1.