The invention relates to the technical field of salt gradient solar pond thermal extraction, in particular to a self-circulation thermal extraction method and device for a salt gradient solar pond. The self-circulation thermal extraction method and device for the salt gradient solar pond are characterized in that one end of a circulation canal is connected with a lower troposphere of the salt gradient solar pond; hot brine under the driving of density contrast caused by temperature difference flows into a heat charge and discharge device arranged on the other end of the circulation canal; brine releases heat in the heat charge and discharge device so that temperature lowers and density increases; and therefore cool brine after the heat releasing flows back to the lower troposphere of the salt gradient solar pond along the bottom of the circulation canal, so that self-circulation thermal extraction is finished. The heat charge and discharge device is provided with a heat exchanger, a cold fluid inlet and a hot fluid outlet, wherein the cold fluid inlet is used for heat extraction for users and the hot fluid outlet is after heat exchange, and thus the heat in the hot charge and discharge device is constantly supplied to users.