To verify the effect of different nursing methods on the potassium efficiency of cotton in seedling stage, the growth and the uptapotassium efficiency and accumulation of potassium in seedling stage of 6 cotton varieties including Xiangnongdamian No.1, Jinnongmian No.2, Xiangfengmian No.3, Xiangzamian No.14, Xiangzamian No.15 and Xiangzamian No.17 were investigated under hydroponics and sand culturing. The results indicated that potassium efficiency coefficients of seedlings with hydroponics were higher than seedlings with sand culturing, which were 0.709–0.865 and 0.559–0.753, respectively. Under sand culturing, Xiangnongdamian No.1 exhibit the highest potassium efficiency while Xiangzamian No.14 the lowest; under hydroponics, Xiangnongdamian No.14 exhibit the highest potassium efficiency while Xiangzamian No.1 the lowest. Under sand culturing, the plant height and main root length of seedling in potassium deficient treatment correspondingly accounted for 67.03%–86.11% and 73.68%–96.61% of those in seedlings with potassium supply. Under hydroponics, the plant height and main root length of seedling in potassium deficient treatment correspondingly accounted for 89.97%–95.64% and 75.68%–91.76% of those in seedlings with potassium supply. Potassium content in above ground parts, under ground part and potassium accumulation in single seedling were significantly higher in seedlings with potassium supply, which were 2.20, 3.17 and 4.37 times as high as those in seedlings without potassium supply under the sand culturing while 2.64, 3.52 and 3.35 times as high as those in seedlings without potassium supply under the hydroponics. The dry matter weight of Xiangzamian No.15 was high with both seeding ways and both potassium treatments, but K content in above ground parts was low, indicating its high tolerance against low level of potassium and high potassium utilization efficiency.