Abstract: Determination methods of available potassium, slowly available potassium and total potassium in soil by ICP-AES were studied and established in this paper. The different forms of potassium was determined by ICP-AES after extraction, the determination results are within the scope of the standard material constant value, the relative standard deviation is less than 4.2%, and the detection limit is between 0.8-1.8 mg/kg. This analysis method is accurate, stable, high sensitivity and accorded with the demands of analysis.