Provided is a dynamic random access memory (DRAM) including a substrate, a plurality of word-line sets, a plurality of bit-line structures, a plurality of capacitors, a plurality of capacitor contacts, and a plurality of air gaps. The substrate has a plurality of active areas. The word-line sets extend along a Y direction and disposed in the substrate. The bit-line structures extend along a X direction, disposed on the substrate, and across the word-line sets. The capacitors are respectively disposed at two terminals of the active areas. The capacitor contacts are respectively disposed between the capacitors and the active regions. The air gaps are disposed in a plurality of spaces enclosed by the bit-line structures and the capacitor contacts. A method of forming a DRAM is also provided.