The synthesis of graphene oxide modified with magnetic iron oxide (Fe3O4@GO) by chemical co-precipitation method and its application for removal of acid fuchsine in the catalytic ozonation process were investigated. The structural, surface, and magnetic characteristics of the nano sized composite were studied by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Vibrating-sample magnetometer (VSM), X-ray diffraction (X-Ray) and Fourier transform infrared spectroscopy (FT-IR). The results showed that the GO plates located between the iron layers and prevent the accumulation of Fe3O4 nanoparticles and, by maintaining the size of the particles, increased the active surface area of the Fe3O4. The nanocomposite was used in catalytic ozonation process and the results were compared with sole ozonation. It was found that, 320ppm of Fe3O4@GO improved removal efficiency of (90%) in comparison with sole ozonation (73%).