A memory system includes a plurality of memory cells. A memory cell includes an anti-fuse transistor, a first select unit, and a second select unit. The anti-fuse transistor has a first terminal, a second terminal, and a control terminal coupled to an anti-fuse control line. The first select unit is coupled to the first terminal of the anti-fuse transistor, a first bit line, and an odd word line. The second select unit is coupled to the second terminal of the anti-fuse transistor, a second bit line, and an even word line. During a pre-screen operation of the memory cell, the odd word line and the even word line are at different voltages.