A method for determination of trace thallium in compound fertilizers by ICP-OES with KI-MIBK extraction wasdeveloped.The sample was digested with aqua regia,and the thallium was enriched by KI-MIBK extraction.The determination was performed with horizontal observation by ICP-OES.The result showed that the calibration curve waslinear in the range of 0～ 1.0mg/L( R2=0.9999).The limit ofdetection(LOD)was 0.014mg/kg.The relative standarddeviation was2.32%(n=7),and the recoveries were from 90.6% to 101%.