Halogens in water are carsinogenic and mutagenic. They are not inherent content of natural water, but an indication of artificial pollution. In the list of 129 chemicals that are designated by U. S. Environmental Protection Agency as “Priority pollutants”, about 60 % are organic halogens. Organic halogens characterized by Absorbable Organic Halogens (AOX) have become an international water quality index. The degreasing agent, pesticide, dry-cleaning agent and bleaching agent that are commonly used in textile dyeing and finishing processes all belong to organic halogens.