Abstract: The study aimed to explore the effects of foliar spraying of different concentrations of sodium selenite on the yield and selenium content of coix seed grains, in order to provide theoretical basis and solution for the selenium-enriched technology of coix seed grains. Two local varieties of coix seed, Guinongyi No. 7 and Xingren Xiaobaike, were selected for the experiment. The sodium selenite at 3, 6, 12 and 24 mg·L⁻¹ (numbered H1-H4) and one clear water control (H0) were sprayed on the leaves of coix seeds during the panicle stage and the grain filling stage, respectively. Each variety and treatment were repeated three times, with a total of 90 experimental plots. Through the uniform planting methods and field management, the yield of coix seed was measured after the grains matured and the samples were collected to detect relevant indicators. The results showed that the selenium content and enrichment coefficient of coix seed increased significantly with the increase of spraying concentration, but the selenium content and available selenium content in soil varied with different varieties and plots, and did not show a consistent linear pattern. In terms of the effect on the yield of the two varieties, Guinongyi No.7 had a certain yield-increasing effect at H1 and H3, while Xingren Xiaobaihe had the same yield level at H0 and H3, and showed significant yield reduction at H1, H2, and H4. The research suggested that the foliar application of sodium selenite during the booting and filling stages of coix seed was an effective measure to increase the selenium content in coix seed grains, especially in the medium and high concentrations (H3 and H4). The selenium content of the two varieties in different plots could meet the requirements of selenium-enriched grains. By considering the improvement effect, cost input and potential risk of grain selenium content, combined with the actual production, the foliar spraying of sodium selenite with the selenium concentration of 12 mg·L⁻¹ and the dosage of 666 L·hm⁻² was the recommended scheme for the production of selenium-enriched coix seed products.