The utility model relates to a multiple-floating-body compound rope mooring device which comprises a deepwater semi-submersible platform with an anchor rack and is characterized in that the multiple-floating-body compound rope mooring device further comprises a floating case, a barge, a plurality of high-strength nylon ropes and a plurality of steel wire ropes, wherein the floating case and the barge are used for assisting moor alongside, and the deepwater semi-submersible platform, the floating case, the barge and a wharf form a multiple-floating-body mooring system; the floating case and the barge are sequentially arranged between the anchor rack and the deepwater semi-submersible platform; the steel wire ropes are arranged between the deepwater semi-submersible platform and the floating case as well as between the deepwater semi-submersible platform and the barge; and the compound ropes of the high-strength nylon rope and the steel wire ropes are arranged between the deepwater semi-submersible platform and the wharf. With the adoption of the mode of the compound ropes of the high-strength nylon ropes and the steel wire ropes, the mooring device provides sufficient mooring force and guarantees the mooring safety of the deepwater semi-submersible platform at the wharf. The mooring device can be widely applied to fabrication, fitting-out and supplying docking process of the deepwater semi-submersible platform with the anchor rack at the wharf.