The invention discloses a Fenton method for efficiently degrading organic pollutants in water. The method includes the steps: adding magnesium-carbon nano-tube compound particles and iron vitriol intowaste water; stirring mixture under the condition of oxygen inlet; controlling a pH (potential of hydrogen) value of solution to reach acidity; adjusting the pH value of the solution to reach 6-9 after reaction; performing solid-liquid separation, and taking liquid supernatant as treatment outlet water. According to the method, hydrogen peroxide of generated by reaction among magnesium-carbon nano-tubes and oxygen and added ferrous ions act to generate strongly oxidizing species such as -OH, and the organic pollutants in the water are completely mineralized into inorganic substances and removed. The method is wide in raw material source, low in price and cost, simple in process, convenient to operate, mild in reaction condition and applicable to large-scale industrial production, and theorganic pollutants are efficiently degraded.