A capacitor with a nano-composite dielectric layer and a method for fabricating the same are provided. A dielectric layer of a capacitor includes a nano-composite layer formed by mixing X number of different sub-layers, X being a positive integer greater than approximately 1. A method for forming a dielectric layer of a capacitor includes: forming a nano-composite layer by mixing X number of different sub-layers in the form of a nano-composition, X being a positive integer greater than approximately 1; and densifying the nano-composite layer.