The utility model relates to a slurry cabin cleaning system in a floating system, and is characterized in that the slurry cabin cleaning system in the floating system comprises a water tank and a high pressure cleaning pump which are arranged on a semi-submersible drilling platform main deck, all slurry cabins which enter a semi-submersible drilling platform floating tank through high pressure lines, and a plurality of nozzles communicated with the high pressure lines are distributed on the cabin walls of the slurry cabins. When being cleaned, the high pressure cleaning pump pressurizes certain pressure to the water of the water tank, and the water forms high pressure water spray through nozzles, so that slurry scale on the cabin walls of the slurry cabins can be cleaned, and then drained by a drainage. The utility model can prevent the workers entering a closed cabin to operate, not only relieves the labor intensity of the workers, but also improves the work efficiency.