The AX-R203 acidic fixing agent is an aromatic sulfonic acid condensate. It is suitable for fixing dyeing of acid dyes or acid fluorescent dyes such as nylon, wool and silk, and metal complex dyes. It can significantly improve the washing fastness of dyes such as nylon, and does not have light fastness and chlorine resistance. Fading has a negative effect. It is compatible with nonionic, anionic surfactants and PVC without any obstacles.