In this paper, we developed a sensitive sensor for phytic acid (PA) and hydrogen peroxide (HO) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). The fluorescence of GQDs@GSH was found to be effectively quenched by Fe ions via photo-induced electron transfer (PET) process. Upon the addition of PA to GQDs@GSH/Fe system, the fluorescence of GQDs@GSH was significantly restored due to the strong chelating and reducing ability of PA, Fe ions could be reduced to Fe ions by PA and formed PA/Fe complex. Therefore, the "off-on" fluorescence method was constructed to detect PA by using GQDs@GSH/Fe as a fluorescent probe. Furthermore, the method can be used for the detection of HO. HO can destroy the chelate structure of PA/Fe, release Fe ions and oxidize Fe ions to produce Fe ions, leading to the fluorescence quenching of GQDs@GSH again. Under optimal conditions, the fluorescence sensing platform showed good linear relationship between the relative fluorescence intensity I/I and the concentration of PA and HO in the range of 0.05-3 μmol L and 0.5-10 μmol L, respectively. The detection limits of PA and HO were 14 nmol L and 0.134 μmol L, respectively. Furthermore, the fluorescence assay method was also applied in real sample analysis and satisfactory results were obtained.