A UV method for the analysis of ascorbic acid with methanol as solvent to prepare a sample has been developed and applied. The effect of copper(II) concentrations on the oxidation of ascorbic acid in aqueous solution has been studied in detail, and the regularities of ascorbic acid oxidation in methanol, USP phosphate buffer (pH 2.50) and de-ionized water have been found. Upon experiments ascorbic acid has been found to dissolve in methanol, and its solubility in it has been measured to be 81.0mg/ml at room temperature (22 degrees C). The ascorbic acid bulk material from a manufacturer has been assayed to be 89.34% with this method, in good agreement with the assay value (89.58%) from the titration method. The ascorbic acid granule and tablet content uniformity also has been tested using this method. This method is simple, rapid, accurate and reliable, and can be adopted for the routine determination of ascorbic acid in its granule and tablet formulations.