An offshore floating wind power combined semi-submersible platform foundation, comprising at least three stand columns, wherein the at least three stand columns form an enclosure of a polygonal structure, adjacent stand columns of the at least three stand columns are connected by using an upper support and a lower support, the at least three stand columns comprises an upper column body and a lower column body, the upper column body and the lower column body are coaxially arranged, a support block is disposed on an upper part of the upper column body, the upper support is positioned on the support block, a lower support connection part is disposed on a lower part of the upper column body, the lower support connection part is connected to the lower support, a front end of the lower support connection part extends beyond an outer edge of the lower column body, a support plate is disposed on a lower side at the front end of the lower support connection part, the support plate is fastened to the front end of the lower support connection part through a ring-shaped buckle, and the lower support is positioned on the support plate.