A noval non-ox idat ive bactericide TS -781 is studied and developed.Its main composition is sulfonated betaine amphiprotic compound with long chain alkyl group.It is suitable for the circulating cooling water of industry and oil field injected water and has a good ef fect on the total general bacteria and sulfate reduction bacteria.The bactericidal effect of TS -781 is superior to dedecy l dimethyl benzyl ammonium chloride.It has an excellent effect on stripping and cleaning germs,algae and slime and also inhibits the corrosion and scale because of the long chain alkyl and sulfonate g roups.