Reactive dyes have been widely used in the dyeing of bright colourful silk fabrics. The discoloration and degradation of Reactive Red K-2G in waste water were discussed in this paper. A new heterogeneous photocatalyst named loading phthalocyanine sulfonic iron fibers (FePcS-F) was prepared by phthalocyanine sulfonic Iron supported by modified cellulose fibers in acidic condition. The photocatalytic degradation of Reactive Red K-2G was characterized by discoloration rate to evaluate the effect of catalyst dosage, catalyst loading (CFePcS-F) and solution pH. The results proved that increasing catalyst dosage and CFePcS-F significantly accelerated the dye degradation. FePcS-F catalyst showed higher photocatalytic activity when the solution’s pH value is equal to or less than 6.0, compared to alkaline medium.