Abstract: As an ideal medical theranostic radionuclide, ¹⁷⁷Lu is widely applied in many cancer diagnostics and therapies. The carrier added 177Lu has the advantages of simple radiochemical process and high irradiation yield. Herein, this paper conducted the research on the preparation of carrier added ¹⁷⁷Lu by thermal neutron irradiation of ¹⁷⁶Lu in the high flux engineering test reactor (HFETR). This work irradiated natural lutetium and enriched ¹⁷⁶Lu. As a result, ¹⁷⁷Lu with specific activity of 0.87 Ci/mg and ^177mLu content of 0.009% was produced by 13 days irradiation of natural Lu at thermal neutron flux of 2×10¹⁴ n·cm^-2·s^-1; ¹⁷⁷Lu with specific activity of 24.9 Ci/mg and 177mLu content of 0.02% was produced by 28 days irradiation of enriched ¹⁷⁶Lu (86.5%) at thermal neutron flux of 1×10¹⁴ n·cm^-2·s^-1; ¹⁷⁷Lu with specific activity of 25.76 Ci/mg and ^177mLu content of 0.002% was produced by 5 days irradiation of enriched ¹⁷⁶Lu (86.5%) at thermal neutron flux of 2×1014 n·cm-2·s-1; and ¹⁷⁷Lu with specific activity of 28.3 Ci/mg and 177mLu content of 0.009% was produced by 12 days irradiation of enriched ¹⁷⁶Lu (86.5%) at thermal neutron flux of 2×10¹⁴ n·cm^-2·s^-1. Among them, both ¹⁷⁷Lu products using enriched ¹⁷⁶Lu targets meet the domestic group requirements with specific activity more than 20 Ci/mg and ^177mLu/¹⁷⁷Lu less than 0.07%. Overall, carrier added ¹⁷⁷Lu which can meet the standards can be prepared by irradiation of enriched ¹⁷⁶Lu in HFETR. It is expected to realize localized production of carrier added ¹⁷⁷Lu according to market demand and promote the domestic researches in ¹⁷⁷Lu nuclear medicine applications.