Abstract: Ion-modified graphite felt was used as electrode of Zn/Fe flow battery. After the graphite felt was treated with H₂O₂, it is placed in a solution of cobalt nitrate and nickel nitrate, which is treated in 60 ℃ water bath for 24 hours. The surface morphology and elemental analysis of the modified graphite felt were carried out by SEM and EDS. In addition, the effect of modified graphite felt on the performance of Zn/Fe flow battery was studied. The results show the oxidation peak and reduction peak was significantly higher, the internal resistance decreases when graphite felt is modified; and when the modified graphite felt as the electrode for Zn/Fe flow battery, the charge-discharge capacity increases and the coulomb efficiency is about 80 %.