The invention discloses a dual-floating-body four-stand-column semi-semi-submersible fan foundation which comprises two long-strip-shaped floating bodies. Four stand columns are vertically arranged onthe floating bodies in two rows, one ends of at least four braced chain lines are correspondingly connected to the four stand columns, the other ends of the braced chain lines are connected to a seabed respectively, the four stand columns are connected with a platform separately, the platform is of a cylindrical structure and is arranged at the top end, a buoyancy tank and a ballast tank are symmetrically arranged below the platform, heaving plates are arranged among the buoyancy tank, the ballast tank and the platform in parallel at intervals, circular installing through holes are formed inthe heaving plates, the stand columns support the ballast tank, the platform and the buoyancy tank through the heaving plates respectively, one ends of tension lines are connected with the bottom ballast tank, and the other ends extend in the direction parallel to a gravity line to be connected to a seabed. The structural stability of the foundation is improved, and the foundation is simple and practical, and is not likely to be damaged.