In this study, we produced a series of environmentally friendly multifunctional additives by polymerization of biodegradable polyethylene glycol (PEG) and N-Vinyl-2-pyrrolidone in different proportions. The copolymer molecular structure was confirmed by Fourier transform infrared spectroscopy, and the impact of the copolymers on dye absorption and dye interaction was investigated. The results showed that the series of copolymers produced displayed enhanced dye decolorization with increasing copolymer dose and time. Additionally, the PEG/polyvinylpyrrolidone (PVP) copolymers and dye molecules interacted; addition of copolymer enabled shifts of the dye λmax toward shorter wavelengths and decreased the UV absorbance. The addition of copolymers reduced the overall Zeta potential of the dye and increased the particle sizes, facilitating dye decolorization. In particular, the dye decolorization effect was the best when the PEG/PVP molar ratio was 8:1.