A duplex document scanning apparatus and method thereof are described. The duplex document scanning apparatus includes a first image sensor, a second image sensor, a switch module, a data conversion unit, and a scanning control device. The first image sensor senses the first analog image signal and the second image sensor senses the second analog image signal. The switch module switches the first image sensor and the second image sensor to select the first analog image signal and the second analog image signal. The data conversion unit converts the first and second analog image signals to generate first and second digital image signals. The switch control module of scanning control device generates a switch signal to control the switch module. The scanning control device has a switch control unit and processes the first digital image signal and a second digital image signal. The switch control unit generates a switch signal for controlling the switch module and the switch module simultaneously outputs the first analog image signal and the second analog image signal to the data conversion unit during a signal period of the switch signal.