A layout of a semiconductor memory device includes a substrate and a ternary content addressable memory (TCAM). The TCAM is disposed on the substrate and includes a plurality of TCAM bit cells, where at least two of the TCAM bit cells are mirror-symmetrical along an axis of symmetry, and each of the TCAM bit cells includes two storage units electrically connected to two word lines respectively, and a logic circuit electrically connected to the storage units. The logic circuit includes two first reading transistors, and two second reading transistors, where each of the second reading transistors includes a gate and source and drain regions, the source and drain regions of the second reading transistors are electrically connected to two matching lines and the first reading transistors, respectively, where the word lines are disposed parallel to and between the matching lines.