Different responses of potassium accumulation and distribution characteristics to potassium stress were studied between sweet potato genotypes Xu28 of high potassium utilization efficiency and sweet potato genotypes Ji22 of low potassium utilization efficiency. The results showed that potassium stress increased the growth of above-part, restrained the root growth, while the change extents were different between the two genotypes. Xu28 had stronger ability in root expanding than Ji22. Potassium concentration in Xu28 seedlings was significant higher than that of Ji22, especially in leaves and petioles, 33.1% and 33.9% higher, respectively. While at harvest period, potassium concentration in Xu28 whole plant was 8.7 g/kg, significantly lower than Ji22 with 9.8 g/kg. Under potassium application or potassium stress, the ratio of potassium distribution of root to shoot were 4.2 and 3.2 for Xu28 and were 2.0 and 1.5 for Ji22, respectively, indicating Xu28 had an ability to dislocate potassium and dry matter to tube root more effectively than Ji22. Potassium use efficiency (KIUE) of two genotypes ranged from 65.1 to 135.9. Xu28 both had significant increase in KIUE under potassium application or potassium stress. The concentrations of potassium in sweet potato shoot, root and whole plant are the dominated factor for potassium use efficiency, indicating higher potassium use efficiency of Xu28 is due to its higher potassium concentrations in leaves, petioles and shoots at seedling stage as well as the higher ratio of potassium accumulation in root to shoot and low potassium concentration in plant.