The invention discloses a method of reducing drinking water disinfection byproducts and belongs to the field of environmental engineering drinking water treatment technologies. According to the method, potassium permanganate is adopted for preoxidation, manganese dioxide generated in the preoxidation process and the potassium permanganate in the coagulation process can be utilized to improve the removal efficiency of macromolecular organic matter in the coagulation process, a ceramic membrane is utilized for entrapment before use of ozone activated carbon, alga substances can be removed, and the situation that alga cells break in the ozone oxidation process to generate new disinfection byproduct precursors is avoided. The concentration of TCM, the concentration of DCAA and the concentration of CH in high-alga surface water treated through the method all meet the requirements of national sanitary standards for domestic drinking water (GB 5749-2006); and compared with a traditional process, the combined process adopted in the method has higher control efficiency on the disinfection byproducts.