[Objective] Desorption of antibiotics in soils in the presence of microplastics is key to its migration, transformation, and bioavailability. The objective of this study was to reveal the desorption characteristics of sulfamethoxazole in an artificial antibiotic contaminated soil in the presence of five different microplastics.[Method] Batch equilibrium desorption experiments were carried out using an acid paddy soil that was spiked with 33.4 mg·kg^–1 sulfamethoxazole and was aged for 5 days before use. Five polymeric microplastics including polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP), and polyethylene terephthalate (PET) (1.67% and 3.33%). The microplastics were added to the soil individually and a soil:solution ratio of 1:10 was maintained in the experiment. The supernate was sampled for the sulfamethoxazole analysis using high-performance liquid chromatography (HPLC) from 0.25 to 96 h during the desorption kinetic experiment. Also, different concentration of NaCl and fulvic acid were added into the soil-microplastics mixture system to study the effect of salinity and dissolved organic matter (DOC) on sulfamethoxazole desorption, respectively.[Result] The results indicated that the desorption rate of sulfamethoxazole declined significantly and a slow desorption phase was observed from 10 h to 48 h after the addition of polyethylene and polystyrene microplastics. The equilibrium desorbed concentration of sulfamethoxazole declined significantly (P < 0.05) in the presence of polyethylene and polyvinyl chloride microplastics. The influence of sodium and calcium ions on sulfamethoxazole desorption from the soil was not affected by the addition of microplastics. However, the influence of fulvic acid on sulfamethoxazole desorption was mitigated after the addition of microplastics in general. Importantly, with an elevated concentration of fulvic acid, the decline of sulfamethoxazole desorption was negligible.[Conclusion] Generally, the desorption of sulfamethoxazole from soils was altered in the presence of microplastics. In soils with a relatively high concentration of DOC, elevated sulfamethoxazole desorption was observed. Therefore, this study highlights the migration and bioavailability of sulfamethoxazole in soils contaminated with microplastics and how different solvents influenced its desorption.