The effects of various parameters on partial decoloration of cotton dyeings using discharge reactive dye were investigated. The decoloration of dyed cotton fabrics with varying pH were very sensitive below 100g/l of amount of potassium carbonate. Our results did indicate any significant changes in color when the amount of Rongalite C in reducing liquor was increased 150g/l to 200g/l. The steaming time had significant effects on fade-out, with an steaming time of 3∼5 min. being sufficient for decoloration build up. The change of color below 130℃ was not significant and it only become evident above 140℃. The additional color changes did not cause by washing under suitable concentrations of oxidation and neutralization agents. The decoloration treatment did not affect the mechanical property of cotton fabrics such as tensile strength.