Abstract: The tantalum in niobium and niobium alloys was determined by Prodigy DC arc spectrometer. The exciting current, buffer, sample to buffer ratio and tantalum element spectral line were determined by experiments. The precision, accuracy and detection limit of tantalum of this method were also determined. Resuts showed that the buffer was the blend of LiCO₃ and C powder with the ratio of 1 to 6, the ratio of buffer to sample was 1 to 2, and 271. 073 nm was chosen to be the spectral line of Ta; the recovery was 94%~109% and the relative standard deviations of the 10 measured values were lower than 10%.