A method for reading data from a storage unit of a flash memory, performed by a processing unit, including at least the following steps: A first read command is received from a master device via a first access interface. It is determined whether data requested by the first read command has been cached in a first buffer, which caches continuous data obtained from a storage unit. A second access interface is directed to read the data requested by the first read command from the storage unit and store the read data in a second buffer and the first access interface is directed to read the data requested by the first read command from the second buffer and clock the read data out to the master device when data requested by the first read command has not been cached in the first buffer.