A 3D memory constituted by multiple layer memories. Each layer of memory includes m word lines, n bit lines and a plurality of initial switch layers, where m, n are natural numbers. The initial switch layer consists of Chalcogenide material. Two initial switches C[i, j +1] and C[i +1, j] are provided in a region surrounded by the word line i, the word line i +1 and the bit line j, the bit line j +1; and no initial switch is provided in a region surrounded by the word line i +1, the word line i +2 and the bit line j, and the bit line j +1, wherein i is odd and 1<=i<=m-1; j is a natural number and j is in a range from 1 to n-1, the initial switch layer C[i, j +1] denotes an initial switch connecting the word line i and the bit line j +1, and the initial switch layer C[i +1, j] denotes an initial switch connecting the word line i +1 and the bit line j. Each initial switch constitutes a memory core along with the connected word line and the connected bit line.