Abstract: The study aimed to explore the effects of applying different concentrations of selenium-enriched organic fertilizers on the yield of coix seed and the selenium content of coix seed grains, in order to provide theoretical basis and solution for selenium-enriched technology of coix seed. Two local coix seed varieties, Guinong No.7 and Xingren Xiaobaike, were selected for the experiment. 14 selenium concentration treatments of 18, 54, 162, and 486 mg·kg⁻¹ were set up（C1−C4）, along with one blank control of 0 mg·kg⁻¹（C0）. Three repeated experiments were conducted for each variety, totaling 30 plots. Through the unified planting methods and field management, the yield of coix seed was measured after the maturity, and the samples were collected to detect the relevant indicators. The results showed that the yield of Guinongyi No.7 had a certain increasing trend under the treatment of some selenium concentration (such as C2 in Plot A1 and C3 in Plot A3), but the increase did not reach a significant level; while Xingren Xiaobaike exhibited a significant decrease in yield under medium and low concentrations (C1 and C2), and only at the higher concentration of C3, the yield could be maintained at a comparable level to the control. The stability of soil pH value was high (coefficient of variation CV＜6%), and there was no significant difference in pH value among the various selenium application treatments within the same plot. The content of selenium in soil increased with the increase of selenium concentration, and the changes in available selenium were complex, which was related to many factors such as variety and soil pH. The selenium content in the grains of the two varieties increased significantly with the increase of selenium concentration. The selenium content of Xingren Xiaobaike was slightly higher than that of Guinong Yi No.7, and the selenium enrichment coefficient in the grains of both varieties increased with the increase of selenium concentration. The research suggested that the basal application of organic selenium fertilizer was an effective means to increase the selenium content of coix seed. When the concentration was higher, the effect of selenium enrichment was more significant. The basal application of C3 concentration selenium-enriched organic fertilizer was the best selenium concentration in this experiment. The selenium content of coix seed in all plots of the two varieties was effectively increased and the ideal selenium-enriched effect was achieved, which was comparable to that of the higher concentration of C4 treatment. Based on the actual production situation, the application of selenium-enriched organic fertilizer with the selenium concentration of 162 mg·kg⁻¹ at the base of coix seed (with an application rate of 4500 kg·hm⁻²) was the recommended solution for the production of selenium-enriched coix seed products.