The role of white rot fungus in the treatment of dye wastewater has been widely researched. Numerous genera of fungi have assumed responsibility for dye decolorization, either in living or dead form. This study looks at the degradation of an acidic dye, indigo carmine (IC), as the medium in an aqueous solution by means of biological degradation in dead fungus of Heterobasidion Insulare. The dye decomposition of reaction time relies on the primary dye concentration, mortality quantity of biomass, churn rate, and primary pH. Experimental results show that an increase in the mortality quantity of biomass significantly affects dye degradation. The highest degradation rate of dye was achieved at 125-150 rpm. Slightly reduced biological activity was found when we reduced the stirring rates. The pH of the reaction system is a slight variation in the 4-8 range, when dye degradation efficiency was not affected so obviously. The dye of color discoloration was observed to occur rapidly within 60 minutes. The degradation of dye by inactivated biomass of H. Insulare definitely depended on original dye-wastewater concentration in the aqueous solution. Dye degradation was reduced from 64% to 93% as the original contents were enhanced from 50 to 500 mg/l. This study was desirable in that it shows it is possible to degrade textile dyes by inactivated biomass of H. Insulare.