In this research, Fe3O4 NPs was synthesized by co-precipitation approach. Then SiO2 shell was grown on the Fe3O4 core. Synthesized NPs were characterized by means of XRD, FTIR, VSM, TGA, SEM and TEM. The magnetic properties of core and core-shell NPs was 74 and 42 emu/g, respectively. The TEM picture of core-shell was showed thickness shell of SiO2 on the Fe3O4 NPs. The size of this shell about 2.5 nm Which caused the core magnetic property to be well preserved. Photocatalyst activity of the synthesized NPs was investigated by using methyl orange (MO) and methylene blue (MB) as pollutant at different pH. For first time sodium citrate was used to improvement photo-degradation. The Fe3O4 indicated good photocatalyst activity for photo-degradation and it's activity was considerably increased after SiO2 shell growth.