Abstract: The paper chromatography method for determination of ¹⁷⁷Lu-EDTMP radiochemical purity was established. ¹⁷⁷Lu-EDTMP was separated from impurities ¹⁷⁷Lu³⁺ under alkaline conditions with V(water)∶V(ammonia)=50∶2 solution as developing reagent and Whatman No.540 as stationary phase. There was a better separation using this method, the R_f of ¹⁷⁷Lu³⁺ and ¹⁷⁷Lu-EDTMP were 0 and 0.9～1.0 respectively. The relative standard deviation was less than 1%. This method was simpler, quicker and suitable for the analysis of radiochemical purity of solution and kit composed of ¹⁷⁷Lu-EDTMP.