The present invention relates to a scanning apparatus with different resolutions. The scanning apparatus includes a casing, a scanning module, a reflective module, a first lens, a second lens, a first sensing element, a second sensing element and a main reflective mirror. The first lens and the first sensing element have a first resolution and are used for scanning a first-sized document. The second lens and the second sensing element have a second resolution and are used for scanning a second-sized document. The main reflective mirror arranged between the first sensing element and the second sensing element for preventing interference of the first sensing element with the second sensing element.