The invention discloses a towel staining method. The towel staining method comprises the following steps: A. pre-treatment: seam turning, desizing, singeing, setting, bleaching, mercerizing and sanding, wherein a liquid used for bleaching is prepared by adding fermentation broth to hydrogen peroxide in a weight ratio of (4.5-5) to 5; B. activity staining: using plant pigments for staining, then using the fermentation broth with weight half the weight of the total plant pigments for fixation and then carrying out cleaning; C. after-finishing: adding water and the fermentation broth to a cleaned cloth to soften the cloth and then carrying out dehydration, drying and stentering setting, wherein the fermentation broth is prepared by the following steps: mixing fresh cellulose, water and brown sugar in a weight ratio of (2.8-3.2) to 10 to 1, hermetically fermenting the mixture for 10-11 months, filtering the product and then taking the liquid. The problems that cotton towels treated by existing staining processes cause big harm to skins and are not easy to fix can be solved by adopting the towel staining method.