Semiconductor photocatalytic oxidation technology has a very wide application in dealing with energy crisis and environmental pollution problems. In this paper, the grapheme was used to modify Zn2SnO4 prepared by hydrothermal method. The structure characteristics of grapheme/Zn2SnO4 were investigated by X-ray diffraction (XRD), Infrared spectroscopy (FT-IR) and Raman spectroscopy. The transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy were used to observe its morphology and analyze chemical composition, respectively. The photocatalytic performance of graphene/Zn2SnO4 photocatalytic degradation of methylene blue (MB) under UV irradiation was investigated by UV-Vis spectrophotometer. The photocatalytic mechanism of degradation of MB was dicussed by photocatalytic experiment with free radical scavenger, electron paramagnetic resonance spectrum and fluorescence spectrum. The stability of the photocatalyst was evaluatedby repetitive photocatalytic experiments. The results showed that the addition of graphene had no influence on the structure and morphology of Zn2SnO4. And when the additive amount of Graphene oxide (GO) is 4Wt%, the grapheme/Zn2SnO4 can exhibited the highest photocatalytic activity. During the photocatalytic process, ·OH was the dominant photooxidant, and there was indirect reaction between ·OH and organic chemical dyes.