In order to solve the problem of energy supply for underwater equipment, wireless power transmission technology is becoming a new way of underwater power transmission. It has incomparable technical advantages over traditional power supply method, and can effectively improve the safety, reliability, convenience and concealment of power supply for underwater equipment. The WPT has a natural electrical isolation between the primary and secondary sides to ensure safe charging in an underwater environment. This breakthrough technology greatly facilitates power transmission in the deep sea. However, current transmission power and efficiency levels are not at the level of WPT systems in air. Based on the analysis of the development status of underwater wireless power transmission technology, this paper firstly puts forward the challenges of underwater wireless power transmission, and summarizes the electromagnetic coupler structure, underwater docking mode, compensation topology, control method and eddy current loss. The current research hotspots in the field of underwater wireless power transmission are summarized and analyzed. Finally, according to the development trend of technology, the urgent technical problems in underwater wireless power transmission are expounded.