The dyeing properties of cotton fabric with Inonotus obliquus are studied by investigating the effect of dyeing conditions on dye uptakes such as, the concentration of Inonotus obliquus, dyeing temperature, time, and pH values. In addition, the effects of mordants on dye uptakes and antibacterial activities are also investigated. The results are summarized as follows: The dye uptakes of dyed fabrics were increased gradually with an increasing concentration of Inonotus obliquus. K/S values were the highest when the dyeing temperature and time were at $60^{circ}C$ and 60 minutes, respectively. As for the changes of pH values of dyeing solution, K/S values recorded the highest at pH3-pH5. Antibacterial activities of Inonotus obliquus dyeing solution showed a significant effect in dyed cotton fabric with mordanting.