The invention relates to the technical field of underwater robots and provides a deep-sea cobalt crust cutting device based on high-pressure water jet flow. The deep-sea cobalt crust cutting device comprises a high-pressure water conveying system, high-pressure water jet flow nozzle units and nozzle supports. The high-pressure water conveying system is in connection with the high-pressure water jet flow nozzle units, the tops of all nozzles in the high-pressure water jet flow nozzle units are arranged on supporting frames, the bottoms of all the nozzles are spherical, and all the nozzles are connected with the nozzle supports through spherical hinge structures correspondingly; and the nozzle supports are each of a hollow frame structure, spherical shells are fixed into frames, jet holes are formed in the spherical shells, and the lowest points of the outer surfaces of the spherical shells are higher than the bottoms of the frames. The deep-sea cobalt crust cutting device based on the high-pressure water jet flow is suitable for the landform of a seafloor cobalt crust of the South China Sea, cutting precision can be improved, and the ore dilution rate is reduced.