A method for replacing data in a system cache includes obtaining, by the system cache, an access statistics value corresponding to each piece of header data in the system cache, wherein the access statistics value corresponding to the header data represents a difference of the predetermined number of access times of the header data minus the number of times that the header data has been accessed by central processing units (CPUs); obtaining, by the system cache according to the access statistics value corresponding to each piece of header data, header data to be transferred; and transferring, by the system cache, the header data, which is to be transferred, to an external memory.