The invention provides a sandstone bottom water reservoir water cone quantitative-description method. The sandstone bottom water reservoir water cone quantitative-description method comprises the steps of 1 collecting an oil reservoir characterization parameter of a researched oil reservoir, 2 describing a model formula by selecting a corresponding water cone or a water ridge according to well type and 3 utilizing the selected water cone or the water ridge to describe the model formula and calculate the morphological parameter and volume of the water cone or the water ridge. By means of the sandstone bottom water reservoir water cone quantitative-description method, the morphologies of the water cone or the water ridge of the oil reservoir at different position in different periods can be predicted, and the residual oil distribution rule of the sandstone bottom water reservoir can be determined. The sandstone bottom water reservoir water cone quantitative-description method has the advantages of being high in prediction success rate, simple and convenient to used and practical.