The invention discloses a semiconductor memory device and a method for word line decoding and routing. The present invention relates generally to semiconductor memory field, Problems solved by the invention is that, to improve the quality of word line signals results in routing congestion. Embodiments of the invention provide the program as follows: a semiconductor memory device and a method for word line decoding and routing, dividing memory array of the semiconductor memory device into a plurality of smaller memory arrays, on a first metal layer routing first decoded row address, on a second metal layer below the first metal layer routing second decoded row address, and the output word line after decoding drives the plurality of smaller memory arrays. Embodiments of the invention are suitable for various semiconductor memory designs, including: on-chip cache, translation look-aside buffer, content addressable memory, ROM, EEPROM, and SRAM and so on.