Abstract: In order to study potassium nutrition feature and the optimum potassium content,‘Yunma 1’was used as test material, the growth characteristic, dry matter, the accumulation and distribution of potassium ion, and the utilization efficiency of potassium under different potassium levels were studied through the method of water culture. The results showed that the growth indexes of hemp such as plant height, stem diameter, leaf area and root/shoot ratio reached the optimal level under 2.0 mmol/L potassium treatment. With the increase of the application amount of potassium, the potassium utilization efficiency and SOD activity of hemp decreased, while the content of chlorophyll increased, the content of sucrose and the activity of sucrose increased at first and then decreased. The dry matter and potassium accumulation amount of hemp reached the maximum level under 2.0 mmol/L potassium treatment, and the potassium distribution in hemp organs was in an order as stem＞ leaf＞ root. In conclusion, the optimal concentration of potassium for hemp growth and development under this experimental condition was 2.0 mmol/L.