A flash memory accessing apparatus is disclosed. The flash memory accessing apparatus includes a controller, a first channel memory set and a second channel memory set. The first channel memory set includes a first flash memory and at least one first memory expanding socket. The second channel memory set includes a second flash memory and at least one second memory expanding socket. The controller determines the accessing method to be implemented on the first memory and second flash memory according to whether there is any flash memory inserted into the first memory expanding socket and the second memory expanding socket.