Abstract: To investigate the effects of treatment duration and material type in reductive soil disinfestation (RSD) on soil biological co-contamination caused by the combined presence of soil-borne pathogens and antibiotic resistance genes (ARGs), farmland soils with severe biological co-contamination were selected as the research subjects. RSD treatments were applied using three durations (10, 20, and 30 d) and three material types: alfalfa (AL), molasses (MO), and a mixture of alfalfa and molasses (m_AL∶m_MO=1∶1, AM), and an untreated control (CK) was also included. Each treatment was conducted for all three durations (10, 20, and 30 d). Changes in the relative abundances and reduction rates of Ralstonia solanacearum, ARGs, and mobile genetic elements (MGEs) under different RSDs were analyzed via real-time PCR. The results show that RSD (AL and AM) had a significant inhibitory effect on the relative abundance of R. solanacearum. As RSD duration increased, the reduction rate of R. solanacearum gradually declined and then stabilized. The effects of RSD duration on different ARGs and MGEs in the soils varied. Extending the RSD duration effectively enhanced the reduction of aadA21, blaCARB and IS6100 genes with the highest reduction rates at 30 d being 49.9%, 58.7%, and 43.9%, respectively. In contrast, the reduction rates of APH(3″)-Ia and tet36 initially increased and then decreased over time, reaching their highest values at 20 d (70.7% and 74.1%), respectively. The reduction rates of the tetG, msrE, and sul1 genes in the soil exhibited a distinct trend of initially decreasing and then increasing with prolonged RSD duration. The RSDs with different material types showed varying effects on reducing soil biological co-contamination. AL was more effective in reducing the relative abundance of R. solanacearum, aadA21, tet36, and qacH genes, whereas AM was more effective in reducing the relative abundance of aadA7, tetG, and IS6100 genes. For the remediation of soil biological co-contamination caused by the combined presence of soil-borne pathogens, ARGs, and MGEs, it is essential to select both the RSD duration and material type strategically in a targeted way to achieve optimal results.