Sulfamethoxazol (SMZ) is a broad spectrum antibiotic which is widely used as bacteriostatic agents in animal husbandry and veterinary practice. Sulfamethoxazol are widely used as feed additives, mainly for fattening of calves and pigs. Sulfonamides are also used in veterinary medicine for the treatment of intestinal infections, mastitis, and other diseases. However, it leads side effects of hematotoxic, agranulocytosis, hypersensitiveness. It will affect urinary system and cranial nerves system. Sulfonamide residues may therefore occur in food of animal origin such as fish and shrimp and lead to a risk for consumers.