Abstract: In order to measure the content of ~(126)Sn in high-level liquid waste, a method of determining~(126)Sn is developed. The principal step of method is extraction with methyl iso-butyl ketone(MIBK). The recovery of Sn is approximately 60%, and analysis can be performed in about 3hours. ~(126)Sn is separated from high--level liquid waste and measured by HPGe γ spectrometersystem. The detected radioactivity of ~(126)Sn in high-level liquid waste is 371±29 Bq/ml, the ratioof which to the total radioactivity of high--level liquid waste is about 4×10~(-7).