The invention provides a novel jet propulsion device and belongs to the field of underwater robots. The novel jet propulsion device is composed of a flexible skin, a carrying main platform, supportingshafts, nozzles, a base, a rotary shaft, pull rods, driven wheels, a driving wheel, a carrying auxiliary platform and a motor. The motor drives the rotary shaft to rotate around the axis, the rotaryshaft drives the driving wheel to rotate, the driving wheel drives the three driven wheels to start rotating, the driven wheels rotate in the same direction, the initial positions of the three pull rods are located at the farthest ends, at the moment, the driven wheels drive the pull rods to move, the pull rods pull the flexible skin to retract inwards, water in a cavity is sprayed out through thethree nozzles, and a robot moves forwards; and when the flexible skin retracts to the minimum state, the driven wheels continuously rotate in the same direction and drive the pull rods to move, the pull rods push the flexible skin to expand outwards, the cavity of the robot starts to be injected with water, the pull rods return to the initial positions, and the above process is repeated. Mechanical gear and connecting rod design is adopted by a body, the structure is simple, and installation is convenient. The water injecting and spraying processes of the robot are achieved through a relatively simple principle convenient to use.