Potassium utilization efficiency (KUE) for plants is related to genotype difference, soil characteristics, application of fertilizer and irrigation. Up to now, the KUE of different genotypes worldwide has been extensively studied, but the influence of environment stress on KUE of cotton is infrequently reported. Thus, we selected a high K utilization efficiency cotton genotype (HEG) and a low K utilization efficiency cotton genotype (LEG) as indicator plants. The results showed that both soil water stress and K stress limited the growth of cotton genotypes. The change of soil water levels had significant influence on yield, KUE, rates of fallen leaves and bolls (RF), biomass and potassium accumulation in cotton. Deficient of soil water restricted the uptake and translocation of K. The absence of soil K greatly increased the proportion of biomass of reproductive organs and K distribution to reproductive organs in this experiment. The HEG exhibited higher physiological compared with LEG under the stress conditions, especially under low K treatment.