Abstract: A radiochemical procedure for separation of ⁹³Nb^m, ⁹⁴Nb from dissolution of spent fuel based on extraction using BPHA, back-extraction using ammonia, and extraction twice by α-benzoin oxime to remove ⁹³Mo is developed. The procedure has decontamination factors of 2.4×10⁶, 1×10³ to ¹³⁷Cs, ⁹³Mo respectively and better than 10⁴ to ¹⁴⁴Ce and ¹⁰³Ru. The efficiency curve at low energy region of broad energy Ge detector was calibrated using standard source of ²⁴¹Am, ¹³⁷Cs and ⁵⁷Co. So the efficiency of ⁹³Nb^m can be known from the curve. Finally, using this detection method and the procedure described before, the ⁹³Nb^m radioactivity in one kind of spent fuel dissolution is determined to be (126.87±4.86) Bq/g, and the specific activity of ⁹⁴Nb is less than 0.05 Bq/g.