A card reader that is connected to a portable electronic apparatus includes a processor and a memory card controller. The processor receives a trigger signal from the portable electronic apparatus when the portable electronic apparatus is in a standby mode. The memory card controller detects whether at least one memory card is inserted into the card reader and generates a memory card inserting status accordingly. The portable electronic apparatus provides a standby power to the card reader and a first screen based on the trigger signal. The processor receives the memory card inserting status; according to the memory card inserting status, the processor reads contents of the memory card, so that the contents of the memory card are displayed on the first screen.