A polishing composition of the present invention at least comprises about 750 ppm to less than 5000 ppm by weight of abrasive particles, hydrogen peroxide, an accelerator, a dual-corrosion inhibitor and water, wherein the dual-corrosion inhibitor contains a first and a second corrosion inhibitor. The dual-corrosion inhibitor is applied to the planarization of metal layers so as to maintain a high removal rate of metal layers as well as suppress etching of the metal, thus capable of reducing polishing defects such as dishing, erosion and the like.