For the development of a highly active and energy-effective electro-Fenton (E-Fenton) process, a simple and efficient electrochemical method was used to modify the nitrogen-doped graphite in situ. It showed that through ammonium nitrate electroactivation, this process could provide (i) a higher surface area, (ii) more hydrophilicity, (iii) much higher electrocatalytic activity toward the oxygen reduction reaction, and (iv) more nitrogen-containing functional groups. The reduction of oxygen to generate H2O2 was promoted, and the current efficiency of the E-Fenton process was also upgraded from 57.96 to 83.76% over 15 min. The apparent rate constant for the dye Brilliant Red X3B by electrochemisty is 0.1781 min(-1), much higher than that of the Raw (0.0731 min(-1)). The dimethyl phthalate (DMP) and the diethyl phthalate (DEP) had the same results. Hydroxyl (center dot OH) radicals were identified as the main reactive oxygen species, which dearly increased after electroactivation.