Abstract: To address the issues of difficulty in cooking, poor texture, and low digestibility of brown adlay millet caused by its bran being rich in crude fiber and wax, while also overcoming the drawbacks of existing modification methods such as high temperature and ultra-high pressure, which lead to severe nutrient loss and high processing costs, this study modified brown semen coicis by cold plasma technology. The processing parameters were optimized, and the nutritional performance and sensory quality of brown semen coicis before and after modification were evaluated. The results showed that cold plasma treatment significantly improved the cooking characteristics of brown semen coicis. The best results were achieved with a voltage of 2 kV, a frequency of 250 Hz, and a treatment time of 5 minutes, at 8 h, the water absorption rate was approximately 46.13%. Under these conditions, the optimal cooking time of brown semen coicis was reduced from 70 minutes to 42 minutes, while the water absorption rate, volume expansion rate, and solid loss rate increased by 31.41%, 22.57%, and 2.28%, respectively. The characterization of the internal structure and gelatinization properties of brown semen coicis indicates that CP mainly reduces the crystallinity of brown semen coicis from 36.32% to 33.43% through an etching effect, significantly decreases the amylose content to 118.4 AM/g kg⁻¹, and the recovery value increased significantly to 445 mP·s, thereby improving the cooking characteristics of brown semen coicis. Nutritional component analysis shows that CP treatment effectively improves the nutrient profile of brown semen coicis: the levels of seven essential amino acids, including isoleucine, were all significantly increased; the content of unsaturated fatty acids (oleic acid, linoleic acid) was markedly elevated; the concentrations of VB₁₂, VD, and VE increased by 50.0%, 31.0%, and 68.6%, respectively; the contenmt of Mg and K increased by 39.5% and 37.3%, respectively; and the polysaccharide content increased from 42.05 mg g⁻¹ DW to 52.97 mg g⁻¹ DW (an increase of 26.0%), which enhances its culinary value. In vitro efficacy evaluation results demonstrate that CP treatment significantly enhances the antioxidant capacity of brown semen coicis, with the DPPH and ABTS⁺ free radical scavenging activity increased to 45.93% and 71.43% respectively. Regarding blood glucose reduction, the IC₅₀ value for inhibiting α-amylase and α-glucosidase activity decreases to 515.45 and 242.50 μg/mL respectively, while the digestibility increases to 29.98%. Sensory evaluation results showed that the odor, color, taste and flavor of brown semen coicis are all improved after CP treatment, the total score increased from 58.1 to 82.2.