Potassium content is an important standard for measuring tobacco quality, however research on low potassium tolerance mechanism in cigar tobacco (Nicotiana tabacum L.), which is different from regular tobacco, did not draw researchers attention. This study evaluated the tolerance to low potassium of 23 cigar varieties by studying 20 phenotypic and physiological indicators. Through principal component analysis, membership function analysis, and cluster analysis, the research comprehensively identifies the tolerance of cigar tobacco varieties to low potassium. The results indicate that the tolerance to low potassium of cigar tobacco is complex and varies with different traits and varieties. The present study identified six crucial indicators for measuring tolerance to low potassium in cigar tobacco leaves, including plant height, maximum leaf area, leaf surface area, total root absorption area, and active root absorption area. Based on the comprehensive evaluation value D of the low potassium tolerance coefficient of these six indicators, the study classified 23 cigar varieties and identified 1 low potassium-sensitive variety, 5 low potassium-low tolerance varieties, 11 low potassium-relative tolerant varieties, and 6 low potassium-tolerant varieties. The research outcomes significantly contribute to the elucidation of tolerance to low potassium in cigar tobacco, facilitating the evaluation, screening, and cultivation of cigar tobacco varieties resilient to low potassium conditions. Additionally, this laid the foundation for exploring scientific issues such as how plants can effectively utilize potassium, the mechanism of potassium ions in plants, improvement and development of cigar quality, augmentation of potassium utilization efficiency, and saving limited potassium resources to ensure long-term safety of potassium.