Abstract: A micro-plot experiment in the field was conducted in four typical indica rice genotypes of potassium efficiencies of utilization. The micro-plot was consisted of a PVP tube with both width and height of 30 cm. i.e. 7. 07 10-2 m2. The tube was inserted into plowing player until subsoil, about 20 cm in the soil. Three clumps were planted in each micro-piot. There were three K levels: 0.1(60kg K2SO4 /hm2) and 2(120kg K2SO /hm2) and two Na levels: 0 and 1 (39. 6kg Na2SO4 /hm2 with three replicates. There were 72 micro-plots in the trial. Four rice genotypes including two k-efficient ones, Xiangaizhao 9 and Xiangzhonuol, one medium K-efficient one, 89- 642 and one K-inefficient one P3299F4-78-3-1B-1 were used. The four genotypes were selected from about 300 genotypes in hydroponics. The results showed that k-efficient genotypes were much better in efficiencies of potassium utilization, economic efficiencies of potassium utilization and resisitance to brown spots than the K-inefficient ones. Grain yield of the K-efficient genotype, Xiangaizao 9 was as much as 3 to 5 times of that of the K-inefficient one, P3299F4-78-3-1B-1.The genntypic differences to sodlum were marked. The contents of potasslum in sho0t System were significantly inversely interrelated with those of sodium (r=-0. 5046**, n=72).