Abstract: Niobium and tantalum in hydrofluoric acid can form a stable solution, and thus the Nb and Ta content of Nb-Ta ore can be determined accurately by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) with a hydrofluoric acid resistant system. The determination method described in this paper for Nb and Ta in Nb-Ta ore, uses the microwave digestion mode of modular small tank and multiple digestion tank assembly (70 tank/group), and hydrofluoric acid resistant system of ICP-OES. This method shortens the dissolution time from 48 h to 1 h. By using a hydrofluoric acid medium the hydrolysis of high-level Nb and Ta in low acid concentration media is avoided. The detection limits of this method are 5.58 μg/g for Nb and 5.87 μg/g for Ta. The result of Nb-Ta concentrate with 19% Nb₂O₅ and 27% Ta₂O₅ is consistent with that acquired by the alkali fusion method and can be used to determine both high-grade and low-grade Nb-Ta ore with 42 μg/g-19% of Nb₂O₅ and 86 μg/g-27% of Ta₂O₅. The main advantage of this method is to accurately determine Nb and Ta in high-grade Nb-Ta ore.