Underwater robots are key equipment for subsea infrastructure inspection and marine environment survey. Subsea wireless charging stations can power underwater robots in-situ effectively. The principle of the magnetic-coupling underwater wireless power transfer technology is introduced first. Then, the structure of the electromagnetic couplers, the topology of the compensation networks, and the analysis of the eddy current losses are critical technologies of wireless charging stations for underwater robots. The technology status and the application progress of subsea wireless charging stations in recent research are summarized. Finally, the development trends of basic theories and applications of subsea wireless power transfer technology are prospected.