Abstract: After sufficient literature survey and summary, the typical benthic small-scale robots are divided into three categories to be analyzed comprehensively according to their operation forms in the sea. 4 key technologies that affect the development of benthic small-scale crawling robots are summarized and analyzed, i.e., seafloor adaptive walking, navigation and positioning, energy supply and lightweight manipulator technologies. Finally, the development trends of benthic small-scale crawling robots are discussed.