An underwater docking system for an autonomous underwater vehicle, the underwater docking system comprising: an underwater station including a base mount fixed to a seabed and a circular frame member supported by the base mount and parallel to a horizontal plane; and an autonomous underwater vehicle configured to dock with the underwater station while sailing through an upper side of the frame member, wherein: the autonomous underwater vehicle includes an underwater vehicle main body, at least one capturing arm (40a, 40b) provided at a lower portion of the underwater vehicle main body, the at least one capturing arm (40a, 40b) including one end coupled to the underwater vehicle main body so as to be rotatable in a forward/rearward direction and the other end at which an engaging hook configured to be engaged with the frame member is provided, and a locking mechanism provided at the lower portion of the underwater vehicle main body and configured to be locked to a front portion of the frame member in a sailing direction of the autonomous underwater vehicle when the engaging hook is engaged with a rear portion of the frame member in the sailing direction, and the underwater vehicle main body has approached the frame member while the capturing arm (40a, 40b) rotates rearward. an underwater station including a base mount fixed to a seabed and a circular frame member supported by the base mount and parallel to a horizontal plane; and a base mount fixed to a seabed and a circular frame member supported by the base mount and parallel to a horizontal plane; and an autonomous underwater vehicle configured to dock with the underwater station while sailing through an upper side of the frame member, wherein: the autonomous underwater vehicle includes an underwater vehicle main body, at least one capturing arm (40a, 40b) provided at a lower portion of the underwater vehicle main body, the at least one capturing arm (40a, 40b) including one end coupled to the underwater vehicle main body so as to be rotatable in a forward/rearward direction and the other end at which an engaging hook configured to be engaged with the frame member is provided, and a locking mechanism provided at the lower portion of the underwater vehicle main body and configured to be locked to a front portion of the frame member in a sailing direction of the autonomous underwater vehicle when the engaging hook is engaged with a rear portion of the frame member in the sailing direction, and the underwater vehicle main body has approached the frame member while the capturing arm (40a, 40b) rotates rearward. an underwater vehicle main body, at least one capturing arm (40a, 40b) provided at a lower portion of the underwater vehicle main body, the at least one capturing arm (40a, 40b) including one end coupled to the underwater vehicle main body so as to be rotatable in a forward/rearward direction and the other end at which an engaging hook configured to be engaged with the frame member is provided, and a locking mechanism provided at the lower portion of the underwater vehicle main body and configured to be locked to a front portion of the frame member in a sailing direction of the autonomous underwater vehicle when the engaging hook is engaged with a rear portion of the frame member in the sailing direction, and the underwater vehicle main body has approached the frame member while the capturing arm (40a, 40b) rotates rearward.