||Interests in conjugated polymers are rapidly growing by reason of the optoelectronic properties such as electrical conductivity, electroluminescence, and chemical sensing ability. As most anions are found in aqueous media, water-soluble conjugated polymers are needed for anion sensing. In general, conjugated polymers have a hydrophobic and rigid main chain, so they have poor solubility in water. We describe the synthesis and characterization of water-soluble conjugated polymer based on benzothiadiazole for fluoride sensing. The side chain of polymer backbone was substituted to amine moieties for the selective detection of fluoride anion species. Furthermore, sulfonate group was introduced in conjugated polymer backbone for water-soluble properties. We reduced prepared polymer which has diamine group by using lithium aluminum hydride. The reduced polymer could interact with fluoride anion with selectivity based on the change in their color and fluorescence intensity.