Here we report a facile and mild synthesis of the sulfonated graphene (PSS-RGO) catalysts by in situ polymerization of sodium p-styrenesulfonate. Graphene sheets can be used as the flat backbones to graft abundant sulfonate groups on both sides. The PSS-RGO catalysts were characterized by 1H Nuclear Magnetic Resonance (1H NMR), energy dispersive spectrometer, Raman spectroscopy, X-ray photoelectron spectroscopy, and so on. The catalytic properties of the PSS-RGO catalysts for the hydrolysis of ethyl acetate and the esterification of acetic acid with ethanol were evaluated, showing that the as-made PSS-RGO catalysts were active for both probe reactions. The possible deactivation mechanism involved in the surface catalysis of the graphene-based acid catalysts has been addressed.