The present invention provides an automatic jet breaking tool for solid fluidization exploitation of natural gas hydrate, which mainly includes an upper joint, an outer cylinder, an inner sliding sleeve, a lockup sliding sleeve, a thrust bearing, a spring, a jet joint, a telescopic jet sprinkler, a plug block and an extrusion seal ring. The present invention mainly adopts the principle of throttling control pressure to control the position of the inner sliding sleeve by controlling a flow rate of a drilling fluid, so as to turn on and turn off the jet breaking tool. The application of the present invention can realize automatic jet breaking of solid fluidization exploitation of the natural gas hydrate, reduce procedures of a round trip operation, and effectively improve the efficiency and safety of the exploitation operation of the natural gas hydrate.