Objective A pretreatment method based on microwave extraction combined with liquid chromatography-inductively coupled plasma mass spectrometry （LC-ICPMS） was established to accurately determine the five arsenic speciations of arsenobetaine （AsB）， arsenite （As （Ⅲ））， dimethyl arsenate （DMA）， monomethyl arsenate （MMA） and arsenate （As （Ⅴ）） in infant rice flour.Methods The samples of infant rice flour were extracted with 1% HNO₃ and microwave extraction at 90 ℃ for 60 min， centrifuged through the membrane， and the extract was analyzed quantitatively by LC-ICPMS.Results The established method showed good linear relationships in the range of 0.1-50 μg/L with the coefficient of determination R²>0.999 9 for the five arsenic species. The recoveries at different spiked levels were 95.20%-102.00%， and the intra day and inter day precision was less than 5%. The limits of detection of the method were 0.006-0.012 mg/kg.Conclusion The microwave extraction pretreatment method was simple and fast， and the quantitative analysis was sensitive and accurate， which was suitable for the determination of arsenic species in infant rice flour samples.