The invention belongs to the technical field of hydrate application and relates to an internal-overflow type continuous hydrate-method sea water desalinating device. The device comprises an inner-layer reactor, an outer-layer reactor, a sensor, a computer control system, a gas circulating system, a fresh water collecting system, a filtered water discharge system and a spraying system. The device has the advantages that the feature that hydrate density is smaller than water, and the hydrate and water are automatically separated and enters the inner layer after the outer-layer reaction kettle generates hydrate crystals; the inner-layer reactor and the outer-layer reactor are used, hydrate generation, separation, cleaning and decomposition are continuously performed under computer control, integrated and continuous hydrate-method sea water desalinating is achieved, and the overall efficiency of the hydrate-method sea water desalinating is increased; the gas circulating system is added, so that economy is increased, and environment protection and energy saving are achieved.