159 genetically-variable rice varieties were tested for low potassium tolerance according to the synthetic appraisal index. The results indicated that there were 18 and 10 rice varieties that were tolerant and sensitive to potassium deficiency, respectively. By deployment of the recombinant inbred lines (RILs) that were derived from the crossing between the varieties of Tainong67 (potassium tolerant) and Zhixi (potassium sensitive), 27 QTLs for potassium deficiency resistance were detected. The LOD values arranged from 2.52 to 9.23, which explained the phenotypic variance of 2.22% to 7.25%. A major QTL qKC-2 was mapped on chromosome 2 of rice. This locus was yet reported, and might encode for an unknown gene that is valuable for future fine mapping and gene isolation. The newly-developed indel markers could be used to rapidly screen the genotypes with potassium deficiency resistance, thus shortening the breeding period. The lines with good agronomic traits and potassium deficiency resistance could be chosen from RILs and applied to rice breeding directly.