With the scaling down of the copper wires, the printability of these wires is more vulnerable to topography variations during the chemical mechanical planarization (CMP) process. Traditional method of inserting dummy polygons is optimized for uniform density, which may not be effective to minimize the topographic variations. In this work, we present a novel methodology to improve the topographical uniformity by optimizing the density of each window. We perform CMP simulation with the use of industry tool. A unified CMP topography weak-point rule and a dynamic dummy insertion algorithm are proposed to determine and correct the density for each window.