A layout method for a printed circuit board (PCB) is provided. The method obtains a memory type of a dynamic random access memory (DRAM) to be mounted on the PCB, obtains a module group from a database according to the memory type of the DRAM, wherein the module group comprises a plurality of routing modules, obtains a plurality of PCB parameters, selects a specific routing module from the module group according to the PCB parameters, and implements the specific routing module into a layout design for PCB fabrication. The specific routing module comprises layout information regarding a main chip, a memory chip and a routing configuration between the main chip and the memory chip.