Abstract: Activity determination of 89,90 Sr in HLLW by N,N,N',N' tetraisobutyl 3 oxo glutaramide(TIBOGA) extraction liquid scintillation counting method is described. First, actinide elements and other related elements are removed from simulated HLLW by TRPO kerosene extraction. Then, Sr 2+ is extracted into TIBOGA n octyl alcohol kerosene phase. The above organic phase is washed by mixed solution of 0.01 mol/L Fe(NH 2SO 3) 2 2 mol/L HNO 3 in order to eliminate disturbance of Ru 3+. Finally, activity of 89,90 Sr in the organic phase is determined by liquid scintillation counting metod. The determination limit of the method is 1.7 kBq/L, the precision is 2 %, the recovery is higher than 97 %, respectively. Gross decontamination coefficient of related elements in simulated HLLW are as follows:>1×10 6 for UO 2+ 2,Th 4+, Pu 4+, PuO 2+ 2,Np 4+, Co 2+ as well as Cs +; >3×10 5 for NpO 2+ 2;>3×10 4 for Zr 4+ ≥2×10 4 for TcO - 4,Pu 3+ and PaO + 2;>3×10 3 for Ru(NO) 3+ >1×10 3 for RE;>7×10 2 for Am 3+.