Abstract: This method has been applied to the determination of As in sulfuric acid leached ore solution by HG-AFS. When the solutions of potassium hydroxide and sulfuric acid are brought together in just the right proportion，they neutralize each other.Thiourea and ascorbic acid are recommended as the reducing reagents in the HCl medium. The method recovery was 100%~102%，the relative standard deviation,1.4%~2.2%，and the detection limit, 3.5×10^-10g/mL,the linear regression equation,IF=8.214×C+9.688，correlation coefficient,0.9994.The test verified that the method is simple,rapid, accurate and reliable with a wide measurement range and is an effective detection method,which also provides a scientific basis for the effect of sulfuric acid leached ore solution on the environmental protection.