The invention provides an unmanned maintenance cabin for submarine cables. A maintenance cabin control system is arranged in a control cabin of a cable maintenance ship; two parallel crawler belts arearranged on the bottom of the rectangular maintenance cabin; the upper part of the rectangular maintenance cabin is provided with two inflatable buoyancy rafts; the outer four corners of the rectangular maintenance cabin are respectively provided with four high-definition cameras; a control cable is arranged at the bottom of the maintenance cabin and passes through between the two crawler belts;the lower part of the maintenance cabin is provided with a submerged layer; the bottom of the submerged layer is provided with a submerged-layer bottom door which is inwardly openable, and the upper part of the submerged layer is provided with a submerged-pressure control device; a maintenance layer is arranged on the upper part of the maintenance cabin; the bottom of the maintenance layer is provided with a maintenance-layer bottom door which is inwardly openable; four seven-function robot arms are arranged in the maintenance layer, forming two pairs of face-to-face seven-function robot arms;four in-cabin high-definition cameras are arranged at the four corners of the maintenance layer; and the seven-function robot arms carry welding devices and high-temperature drying guns. The underwater unmanned maintenance cabin provided by the invention is convenient and quick in cable maintenance due to usage of the submerged layer and the maintenance layer and is applicable to maintenance of submarine cables.