Milk with total arsenic in the past,was hard to identify the organic and inorganic arsenic in the milk of health assessment of arsenic.This method uses hydrochloric acid extraction,separating the samples of organic and inorganic arsenic.Using the hydride atomic fluorescence spectrometry to determine inorganic arsenic in liquid grandma,this method was simple,rapid,accurate and stable,the recovery of 90 %-102 %,detection limit for 1 μg/L.