The invention belongs to a polymer organic fungicide, and particularly relates to an amphoteric asymmetric efficient fungicide for polymer-contained sewage. The amphoteric asymmetric efficient fungicide is prepared in the mode that tertiary amine, hydrogen chloride and epoxy chloropropane react according to the molar ratio of (1 to 3):1:(1 to 3) to obtain a midbody 1, then the midbody 1 reacts with phosphorus oxychloride according to the using amount ratio of (0.25 to 0.35 mol): (25 to 30 ml) to obtain a midbody 2, the midbody 2 reacts with sodium hydroxide to obtain a midbody 3, through the using amount of the sodium hydroxide, an aqueous solution of the midbody 2 is neutral, and finally, the midbody 3 and metronidazole react according to the molar ratio of (0.9 to 1.1):1. The prepared amphoteric asymmetric efficient fungicide belongs to a novel water treatment system fungicide with good sterilization performance, and can be used for the fields of controlling bacteria in the polymer-contained sewage of an oil field, treating sewage discharged by a factory, and the like.