The invention relates to a rounded inverted prismatic platform shaped floating type production oil storage device which comprises a floating body, an upper combined mould and mooring anchors, wherein the floating body is formed by an upper axial symmetrical rounded inverted prismatic platform shaped structure and a lower axial symmetrical rounded prism shaped structure; a central cabin, a cylindrical oil storage cabin, an upper technical equipment setting cabin and an edge pressing load cabin are arranged in an upper floating body; the central cabin is cylindrical and is inserted into the bottom center of a lower floating body; the cylindrical oil storage cabin is arranged on the periphery of the central cabin; the upper technical equipment setting cabin is arranged on the periphery of the cylindrical oil storage cabin; the edge pressing load cabin is arranged between the upper technical equipment setting cabin and an outer wall of the floating body; the upper floating body is welded with the lower floating body; the central cabin, the cylindrical oil storage cabin and the lower axial symmetrical rounded prism shaped structure are welded; a main generator module is arranged in the rear center of the upper top surface of the floating body; an oil gas processing module is arranged on the front left part; a water processing module is arranged on the middle left part; a heat medium heating mould and a living building module are arranged on the middle right part; and the mooring anchors are symmetrically arranged at four symmetric rounded corners or the outer wall of the floating body between the rounded corners of the lower part of the floating body.