To compare the differences of the active ingredient contents and the sulfur dioxide residue in Astragali Radix before and after sulfur fumigation and provide a basis for establishing an alternative processing method. Astragali Radix, harvested at the same time in Longxi Gansu, were processed with different methods. high performance liquid chromatography (HPLC) was used to determine the contents of the active ingredients in Astragali Radix and the revised method of the pharmacopoeia of China in 2011 was applied to determine the sulfur dioxide residue. The results show that the three-fold sulfur-fumigation group has the highest level of astragaloside IV and the dried sulfur-fumigation group with 10% water has the lowest level; the content of calycosin-7-O-β-D-glucoside is the highest in naturally dried group and the lowest in the group of sulfur fumigating for 3 times; the sulfur dioxide residue of all sulfur-fumigation groups exceeds certain limit significantly and the group of sulfur fumigating for 3 times reaches the highest level.