Abstract: The content and intensity ratio of rare earth in samples were determined by ICP-AES and full spectrum spark direct reading method, and the database of content and intensity ratio was constructed. The standard analysis curve suitable for spark direct reading spectrometer was drawn in combination with the selected analysis lines, so as to realize on-line rapid analysis and detection of rare earth lanthanum, cerium and yttrium in steel. Studies have shown that the correlation coefficients of the standard analysis curves drawn under the 2 analysis lines selected for lanthanum, cerium, and yttrium basically meet the requirements of greater than 0.999, which met the requirements of the laboratory. The contents of lanthanum, cerium and yttrium in the test sample were determined under the drawn standard analysis curve and compared with the results determined by ICP-AES. The results show that compared with the standard analysis curves La^#2, Ce^#1 and Y^#1, the difference range between the measured contents of La^#2, Ce^#1 and Y^#1, the deviation rate is smaller, and the repeatability and accuracy of the detection results are better.