The invention discloses a control method of an image sensor. The method includes following steps: S1, controlling pixels of the image sensor to perform long integration and short integration; and S2, calculating the practical saturated primary color value through an unsaturated primary color value and a primary color value proportion among the three primary color values for short integration when any one of three primary color values for long integration of the pixels is saturated. The invention also provides an image sensor. Therefore, according to the image sensor and the control method thereof, the dynamic range is expanded, and the increase of dark current and noise is avoided.