The power supply for unmanned underwater vehicles has been an important research point since the vehicles were invented. The power systems and environmental energy conversions for the vehicles are reviewed in the paper. Several topics are represented: problems and general solutions for unmanned underwater vehicles power supplies; the mechanisms and structures of tether power system; characteristics of several batteries; the characterization of potential environmental energy, and energy conversion for unmanned underwater vehicles. Docking stations for underwater vehicles continuation are also represented in the paper. Some typical vehicles powered by the power systems and their performances are listed and analyzed.