Abstract: Four ramie genotypes (Boehmeria nivea L.) were used in this study, two of them were high efficiency while the other two were low. Pot experiment and laboratory analysis were conducted. We investigated root growth characteristics, fiber yield and quality for different potassium efficiency ramie genotypes under lower potassium stress, and founded that the lower potassium stress led to decrease in shoot biomass, hindered root growth, decreased root absorption surface area and cation exchange capacity. Under lower potassium stress, the high efficiency ramie genotypes had higher growth potential (higher relative root dry weight, relative rootlet dry weight, relative root total and active absorb surface area), and higher relative fiber yield, decreased the negative effect of lower potassium stress on fiber quality validly.