The invention discloses a movable/fixed man-made island cylindrical foundation which consists of suction anchors, circular-arc apron plates, an annular flat plate and triangular supporting plates, wherein six suction anchor cylindrical foundations are uniformly distributed below the seafloor scour-resistant annular flat plate; six circular-arc apron plates are positioned between two adjacent suction anchors respectively and are connected with the upper parts of the suction anchors and the annular flat plate; the triangular supporting plates are arranged on the middle positions of the six suction anchors; and six frustums and six taper holes are arranged above the annular flat plate. The movable/fixed man-made island cylindrical foundation has the advantages that the structural form is optimized, the structural weight is reduced, and overall installation can be performed under the action of a floating crane in the offshore installation process; moreover, the structural bearing capacityis enhanced in the structural form, and the structural rigidity and the horizontal bending resistance are enhanced; the structure is easy to install and the offshore installation construction period is shortened, so that the engineering cost can be remarkably lowered; meanwhile, the structure is movable, so that the aim of recycling is fulfilled.