The method for indirect determination of atropine sulfate by inductively coupled plasma - atomic emission spectroscopy (ICP -AES) is studied. In the pH5.0, the atropine sulfate is completely precipitated by excessive sodium tetraphenylborate, and the surplus is precipitated by excessive potassium chloride. The potassium in filtrate is detected by ICP - AES for calculating the content of atropine sulfate. The average recovery is 96% - 102% and RSD is less than 1.2%.