Abstract: Based on ultrasound-assisted extraction, a method for determination of inorganic arsenic in various supplementary food for infants and young children was established. The samples were successively subjected to ultrasonic extraction, n-hexane purification, membrane filtration, and anion column (PRP-X 100, 10 μm, 4.1 mm×250 mm) separation. Then, 15 mmol/L diammonium hydrogen phosphate solution (pH=6.0) was used as the mobile phase. After isocratic elution, it was detected by atomic fluorescence spectrometer. The results showed that the linear relationship of arsenic forms was good in the concentration range of 5~100 ng/mL, with correlation coefficient of each component of above 0.999. The detection limit of the method was 0.010 mg/kg. The recoveries of inorganic arsenic at three spiked concentration levels ranged from 88.7% to 96.3%, and the relative standard deviation (RSD) was 1.8% to 4.9%. The method had the advantages of simple pretreatment, high extraction efficiency, fast analysis speed, high accuracy and good repeatability. Therefore, it could meet the detection requirements of different forms of inorganic arsenic in various supplementary food for infants and young children.