Abstract: In this study，hydroponic experiments were conducted to investigate the uptake rates and accumulation of thallium（ Tl+ and Tl3+） in four types of plants and the effect of K+ on accumulation of Tl+ and Tl3+ in plant. The results showed that the uptake rates and accumulation contents of two thallium valence states were different. Nephrolepis auriculata had he greast uptake rates for Tl+ and Tl3+，which were 0.004 mg/g·h and 0.007 mg/ g·h，respectively. The maximum accumulation of Tl3+ in watermifoil was 681.97 mg/kg（DW），and the maximum accumulation of Tl+ in cabbage was 473.30 mg/kg（DW）. The uptake and accumulation of two valences were mainly concentrated in the roots. The valence state in plant roots was Tl+. When the ratio of Tl+/Tl3+ to K+ were 1∶25，K+ had an antagonistic inhibitory effect on the uptake of Tl+ and Tl3+，which could restrain the accumulation of thallium（Tl+ and Tl3+）in plants.