The invention discloses a submarine shallow layer natural gas hydrate pilot hole pull-back jet break-up exploitation method and exploitation device, and belongs to the technical field of submarine hydrate exploitation. The exploitation method mainly comprises the following steps that a water insulation pipe is lowered to the position adjacent to a hydrate deposit, turn drilling is conducted in thehydrate deposit by means of mechanical or jet-flow drilling, and a pilot hole with a certain inclined angle is formed; after drilling reaches a preset position, a continuous pipe and an exploitationcrushing system are pulled back, meanwhile the surrounding hydrate ore body is crushed by means of a spray head jet flow, hydrate particles formed are collected into a closed pipeline with seawater, silt in the crushed particles is separated out by means of an in-pipe downhole separator, curing agent is added, then the particles are backfilled to a gob in situ, and the hydrate particles after separation are pumped to the sea surface for treatment together with the seawater. By means of the exploitation method and the exploitation device, efficient, safe and sustainable exploitation of the submarine shallow layer natural gas hydrate is achieved, the exploitation efficiency is ensured, and meanwhile a potential safety problem is effectively avoided.