The invention relates to a CMOS-TDI image sensor and a formation method thereof. The CMOS-TDI image sensor comprises a substrate, a first channel, a first gate structure and a second gate structure, wherein the substrate comprises a first region and a second region which are adjacent to each other, first ions are arranged in substrate at the first region and the second region, the first channel isarranged in the substrate at the first region, second ions are arranged in the first channel, conductive types of the second ions and the first ions are opposite to each other, the first gate structure is arranged on a surface of the first channel, and the second gate structure is arranged on a surface of the substrate at the second region. The CMOS-TDI image sensor is relatively high in charge reading-out efficiency and relatively small in dark current.