The invention relates to a seabed surface layer natural gas hydrate exploitation method and an exploitation device in the field of natural gas extraction. The seabed surface layer natural gas hydrates can be conveniently cut and are pumped to a working ship through a tubular column so as to finish decomposition and utilization. According to the technical scheme, the method comprises the following steps: driving a rotating disc to rotate by using a diesel engine, transmitting the torque to a cutting head by the rotating disc through the tubular column, an adjusting arm and a reducer, and cutting the seabed surface layer natural gas hydrates with cutting teeth on the cutting head; starting a slurry extraction pump on the working ship, sucking slurry of the natural gas hydrates through a suction nozzle, allowing the slurry to flow through the adjusting arm and the tubular column, and finally allowing the slurry to flow into natural gas hydrate decomposition equipment; and collecting the separated natural gas to be linked with a user end in the decomposition equipment, and discharging the separated water and sand into the seabed. The exploitation method is simple in principle and practical, and the seabed surface layer natural gas hydrates can be conveniently and continuously extracted; and moreover, the exploitation device is simple in structure, low in energy consumption and easy to implement and is used for producing the seabed surface layer natural gas hydrates.