Microplastics, as an emerging pollutant, are widely concerned about because they are easily turned into carriers for antibiotics and other pollutants once they enter the aquatic environment, thereby altering the original environmental behavior of these pollutants. The adsorption characteristics and mechanisms of three common types of microplastics (polyethylene, polypropylene, and polystyrene) on two sulfonamide antibiotics (sulfadiazine and sulfamethoxazole) were investigated. It is demonstrated that the pseudo-second-order kinetic model more accurately describes the adsorption process of antibiotics onto microplastics, indicating that the adsorption behavior involves multiple stages and is influenced by various factors. It is found through model fitting that the Langmuir isotherm model is more suitable for describing the adsorption of SDZ and SMX on PE, PP, and PS, suggesting that the adsorption of these two antibiotics by microplastics is likely to be a monolayer adsorption process. These findings not only reveal the interaction mechanisms between microplastics and antibiotics but also provide a more comprehensive theoretical basis for assessing the potential ecological risks associated with different types of microplastics.