Abstract: Fenton and Fenton-like system enhancing agent and the usage thereof are provided. It relates to a water treatment enhancer (enhancing agent) and the usage thereof. It widens water pH range of Fenton and Fenton-like system reaction. It reduces amount of Fe2+ required for Fenton reaction. It increases rate of Fenton-like reaction. The enhancing agent is selected from sodium sulfite, lithium sulfite, potassium sulfite, magnesium sulfite, calcium sulfite, hydroxylamine hydrochloride, hydroxylamine perchlorate, hydroxylamine sulfate, hydrazine, N,N-diethylhydroxylamine, amino ethanolamine, hydroxylamine solution or N,N,N?,N?-tetrasubstituted p-phenylenediamine. The method of use of enhancing agent comprises the steps of: adding Fenton or Fenton-like system enhancing agent, an agent for enhancement and hydrogen peroxide into water subject to treatment; and mixing and allowing reaction. The enhancing agent can increase the rate of reaction for the water treatment and reduce the dosage of the agent for enhancement.