The invention discloses a fluid loop system suitable for a multi-cabin spacecraft, and belongs to the technical field of multi-cabin spacecrafts. The fluid loop system comprises cold plates, fluid pipelines, a radiator, four liquid path detachable connectors and a separation device. The two cold plates are installed between an in-cabin device and the upper surface of an instrument plate as well as between an in-cabin device and the lower surface of the instrument plate correspondingly, and annular holes of the two cold plates communicate through the pipelines. The radiator is fixed to the outer surface of a sealed cabin. The liquid path detachable connector I and the liquid path detachable connector II are installed at the butt-joint position of a braking cabin and a service cabin through the separation device. The liquid path detachable connector III and the liquid path detachable connector IV are installed at the butt-joint position of a recovery cabin and the braking cabin. One ends of the two fluid pipelines are connected with the annular holes of the cold plates correspondingly, and the other ends of the fluid pipelines pass through the liquid path detachable connector III or the liquid path detachable connector IV, and the liquid path detachable connector I or the liquid path detachable connector II in sequence, then penetrate through the shell body of the service cabin and are connected with the tubular structure of the radiator. According to the fluid loop system suitable for the multi-cabin spacecraft, the gesture of a returning cabin is not influenced through layout of the fluid pipelines and connection design between the cabins.