The present invention relates to a memory-refreshing method applied to a computer system. The computer system includes a central processing unit (CPU), a north bridge chip in communication with the CPU and a system memory in communication with the north bridge chip. The system memory includes at least a first storage zone and a second storage zone. The first storage zone stores a specific data that remains refreshed when the CPU is in a first power-saving mode. The method comprising steps of: refreshing the first storage zone and the second storage zone respectively according to a first clock enable signal and a second clock enable signal generated by the north bridge chip when the CPU is in a normal operation mode; and remaining refreshing the first storage zone according to the first clock enable signal while suspending the second storage zone from being refreshed according to the second clock enable signal when the CPU is in the first power-saving mode