There are 92 kinds of impurity ions in seawater, causing a serious impact on hydrogen production process. Compared with conventional water electrolysis, there will be severe criteria on critical materials and equipments for direct seawater electrolysis. There are still many technical barriers, challenges in engineering or large-scale for direct seawater electrolysis, and there are no advantages of the cost of whole process, limiting its commercial development extremely. In this paper, the reaction mechanism, technological difficulties and research progress are first summarized. Then, the solution and technological breakthroughs for anionic corrosion, cationic deposition and the side reactions of impurity ions are reviewed, including anode/cathode electrodes, electrolyte regulation, reaction substitution and system integration optimization. In the end, the commercial challenges and existing problems in direct seawater electrolysis are analyzed and commercial prospect is prospected.