In order to investigate the decomposition characteristics and nutrient release patterns of cover crops applied individually or jointly in red soil uplands. A 112-day field decomposition experiment was conducted in a typical red soil upland in Jiangxi Province, China, which focused on two cover crop species: Raphanus sativus (Brassicaceae) and Vicia villosa (Leguminosae). Three treatments were tested: Raphanus sativus alone, Vicia villosa alone, and their combination. Decomposition and nutrient element release were monitored using the nylon mesh bag method during the peanut growth period. The results show these as follows. Cover crop decomposition shows a “fast-slow” two-phase pattern. During the rapid decomposition phase (0~28 d), Vicia villosa exhibits the highest cumulative decomposition rate (73.96%), significantly surpassing Raphanus sativus (63.51%) and the combination treatment (68.63%). By 112 d, Raphanus sativus achieves the highest decomposition rate (94.11%), exceeding Vicia villosa (90.72%), with the combination treatment showing intermediate results (92.47%). Nutrient release varies by species: Vicia villosa releases nitrogen, phosphorus, and potassium more quickly, with cumulative rates exceeding 90% at 28 d, significantly higher than Raphanus sativus. In contrast, Raphanus sativus shows higher calcium and magnesium release (94.88% and 93.39% at 28 d, respectively) compared to Vicia villosa (90.04% and 88.05%). Over 75% of the nutrients are released within 28 d, with limited supply thereafter. The combined application of Raphanus sativus and Vicia villosa moderates the rapid nutrient release from Vicia villosa while compensating for deficiencies in secondary nutrients (calcium, magnesium). These findings highlight that the co-application of Raphanus sativus and Vicia villosa optimizes nutrient release timing, enhances soil fertility, and improves synchronization with crop demand. The result provides a theoretical framework for the optimal use of cover crop resources in the red soil hilly region of South China, with practical implications for improving soil health and agricultural productivity.