Abstract: The application of nitrous oxide-ethyne flame atomic absorbing spectral method to measure the content of silicon in Cd-Ni batteries impregnating solution is studied. The optimum measuring conditions for silicon and potency in which a fine liner range presents is introduced, and makes a synthetic consideration to interference factors. The method has the advantages of high sensitivity,And this method is proved, to be simple operation, easy master, short analyzing cycle, less interference and good in selectivity and reappearance. The relative standard deviations are all less than 1.0% in six sample measures, and the standard adding recovery is the range of 97%～103% in six sample measures the practice shows that the method is fully suited to measure the silicon content in Cd-Ni batteries impregnating solution. The proposed method was proved to be a useful instrument analytical technique in nitrous oxide-ethyne flame absorbing spectral method.