It is found that light ink leads to low ratio of coloration in digital textile printing process. So it is important to control the total amount of light ink. In this paper, a new approach is presented to control the use of light ink. It takes the total ink amount into account as well as the linearization of single ink (regard dark ink and light ink which has similar hue as single primary ink). An algorithm is developed to reduce the amount of light ink under the premise of avoiding the graininess appearance. As a result, the color gamut of textile printer is extended extremely, especially in the dark area.