GO/GA-g-PAMPS composite hydrogel was prepared by one-step hydrothermal reaction with Graphene Oxide (GO), gum Arabic (GA) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) as raw materials.The structure of the hydrogel was characterized by FTIR, XRD and SEM.The effects of GO concentration, solution pH, initial dye concentration, adsorption time and adsorption temperature on the adsorption properties of cationic dyes methylene blue (MB) and crystal violet (CV) were studied.The results showed that the hydrogel had a good adsorption effect on cationic dyes. When the GO concentration was 0.3mol/mL, the gel dosage was 0.05g, the solution pH was 7, the temperature was 50℃, and the initial dye concentration was 200mg/L, the adsorption capacity and adsorption rate of the gel on MB and CV were 395.68, 381.70mg/g and 98% and 96%, respectively.After 5 cycles, the adsorption rates of MB and CV were still up to 82.6% and 81.2%.The adsorption isotherm and kinetics showed that the adsorption of MB by gel was more consistent with Freundlich model, while the adsorption of CV was more consistent with Langmuir model, and the quasi-second-order kinetic model could better describe the adsorption process of two cationic dyes.Thermodynamic studies showed that the adsorption of the two dyes by the composite hydrogel is spontaneous, endothermic and chaotic.