The scanning apparatus includes a movable chassis and a main board fixed on the body. A charge-coupled device module and a front end processing device are disposed on the chassis. An application-specific integrated circuit is positioned on the main board. After the charge-coupled device module detects a light analog signal, the application-specific integrated circuit communicates with the front end processing device through a command interface. Therefore, the light analog signal is converted into the light digital signal by the front end processing device, and then the light digital signal encoded into low voltage differential signaling form is transmitted to the application-specific integrated circuit for proceeding the subsequent image processing.