Abstract: Amethod for the determination of phosphorus in gasoline by molybdovanado-phosphoric acid spectrophotometry is proposed. The interference ions probably presented in gasoline are examined, and the optimum determination factors are determined. For the determination of the synthesized samples and gasoline samples the relative error is less than ±3.0%, relative standard deviation is less than 2.30%, and rate of recovery of phosphorous is 98.8%～103.9%. The method is simple and convenient.