Abstract: A simple and rapid UV spectrophotometric method for simultaneous determination of pyruvic acid and lactic acid in their mixture was proposed. Pyruvic acid was determined in strong alkaline medium by using dual-wavelength spectrophotometry and Linear equation (C=6.75×10-3+0.626A) was obtained. Beer's law was obeyed in the range from 0.0505 to 0.5050μg/mL, the determination of lactic acid could be carried out directly in acid medium with good accuracy, a linear relation (C=1.547+51.76A) in the range from 1.22 to 244μg/mL. The method had been applied to evaluate catalytic oxidation reaction in the synthesis of lactic acid and the result attained was identical to one by mean of HPLC, however, this method was more convenient, easier and suitable for online analysis of the industrial products.