Abstract: An analitical method for 129I in liquid effluent of nuclear facility is studied .Anion exchange resin is used to concentrated the iodine in water sample,it is extracted by CCl 4 and stripped by NaHSO 3 solution, 129I is measured by HPGe γ spectrometer in the form of AgI precipitation,it can also be determined by liquid scintillation analyzer directly after purification.For γ spectrometer measurement,the counting efficiency is deduced with the increasing of mass thickness.For liquid scintillation analyzer,it has counting efficiency of 85%.The lowest detective limits of the method is 0.016 Bq/L and 0.037 Bq/L for γ spectrometer and liquid scintillation analyzer,respectively,while the counting time is 1 000 min and 100 min respectively.The whole process recovery is range of 60%～85%.