Hydrothermal method was used to prepare graphene with good water-solubility selecting graphene oxide as precur-sor in alkaline environment.Scanning electron microscopy（SEM） and powder X-ray diffraction（XRD） were used to character-ize the structure and morphology of as-prepared graphene.The electrocatalytic property of graphene electrode on ascorbic acid was investigated using various elecrochemical testing techniques.The results showed that the electrocatalytic oxidation activity of ascorbic acid on this graphene electrode was significantly enhanced.The response peak current of ascorbic acid was optimum under the condition of pH =6.99.Under the optimized experimental conditions,the response current of ascorbic acid was linear well with its corresponding concentration in the range of 1×10^-4~1×10^-3 mol/L.The linear regression equation was I（A）=14 927.87c（mmol/L）+41.19 and the linear correlation coefficient R²=0.998 9.Compared with the standard method,this method applied to the determination of vitamin C tablets has higher accuracy.