In order to achieve 5 degrees of freedom (DOFs) movement in an underwater space with only two moving parts, a new kind of unmanned underwater vehicle, Fan-wing Underwater Vehicle (FUV), is proposed. The FUV is driven by two fan-wings which are adapted from the fan-wings for aircraft. The features of the underwater fan-wing are analyzed by 2D computational fluid dynamic (CFD) simulations. In order to analyze the movement of the FUV, a 6-DOF hydrodynamics mathematical model is built. The model is simplified for analyzing two kinds of common conditions movements. According to the simplified model of the ideal straight-line depth-keeping cruise with constant velocity condition, a general procedure to design the FUV is put forward. Some 3D CFD simulations are added to solve the mathematical model in the procedure of the FUV design. Then, according to the design procedure, a control system and a mechanical structure of the FUV are designed. Finally, a real FUV is manufactured, and an underwater test is completed. The experiment shows that the real FUV can achieve 5 DOFs movement in an underwater space, and the results match the design proposes.