The increasing demand for carbon emission reduction has drawn wide attention on the green hydrogen-manufacturing technology. Hydrogen production by water electrolysis based on renewable energies has the lowest carbon emission among the main hydrogen manufacturing methods. This study summarizes the hydrogen demand, hydrogen industry planning, and demonstrations of hydrogen production by water electrolysis. The water electrolysis technology is analyzed, including alkaline water electrolysis and proton exchange membrane (PEM) water electrolysis. Research reveals that improving electrocatalyst activity, catalyst utilization, bipolar plate surface treatment, and electrolytic bath structures helps optimize the performance of PEM electrolytic baths and lower equipment cost. The PEM water electrolysis has high operating current density, low energy consumption, and high output pressure; therefore, it accommodates the fluctuation of renewable energy power generation and can be easily combined with renewable energy consumption. Considering the technical characteristics of hydrogen transportation and electrolytic hydrogen production as well as hydrogen transportation demand in China, a solution for green hydrogen generation and long-distance transportation is proposed. High-