A dynamic random access memory and its manufacturing method are provided. The memory includes a buried bit line, a plurality of buried word lines, a bit line contact structure, and a conductive plug. The buried bit line is formed in a substrate. A bottom surface of the buried word line is higher than a top surface of the buried bit line. The bit line contact structure is formed on the buried bit line and has a through hole. The bit line contact structure is not in direct contact with the buried bit line. A material of the bit line contact structure is different from a material of the buried bit line. The conductive plug is formed between the bit line contact structure and the buried bit line and fills the through hole, so that the bit line contact structure and the buried bit line are electrically connected.