Abstract: The sample of low alloy steel was polished by abrasive zirconia sandpaper with particle size less than 0.155 mm, and then cleaned by ethanol. Trace amount of niobium in the sample was determined by spark discharge AES. The pre-burning time was selected with 4 s and the analysis time was selected with 5 s. The 210.94 nm spectral line was selected as the niobium analysis line, and the interference coefficient plus mode was used to correct the interference from vanadium. The calibration curve equation between the relative spectral intensity of niobium and its mass fraction was y=0.030 35 x²+0.218 85 x-0.002 525, with detection limit of 0.000 6%. The proposed method was analyzed to the sample of low alloy steel, and values of RSD (n=11) were found in the range of 8.3%-13%. The proposed method was used to the determination of niobium in standard material, giving determining values in accordance with the certified value.