Abstract: Microplastics in the atmospheric environment exhibit a global distribution and complex physicochemical properties. They can be transported over long distances and adsorb various toxic pollutants, posing potential threats to ecosystems and human health. Currently, there is no unified standard for the detection and analysis methods of microplastics, and existing detection and analysis methods all have certain limitations. The Py-TD-GC/MS method, which combines tube furnace pyrolysis, thermal desorption, and gas chromatography-mass spectrometry, has improved sensitivity, accommodates entire air filter membrane samples, and can avoid interference from complex environmental matrices. It can qualitatively and quantitatively analyze five common types of microplastics: polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). In this study, we conducted a qualitative and quantitative analysis of microplastics with a diameter of less than 2.5 μm in the atmospheric environment using the Py-TD-GC/MS method and scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX) to reveal their pollution level in the atmospheric environment of Beijing. The results showed that the abundance of microplastics with a diameter of less than 2.5 μm in the atmosphere was 0.181-1.051 μg/m³, with an average value of （0.405±0.314）μg/m³. The mass concentration of polymer types was in the order of PE>PVC>PET>PS, and PP was not detected. In the future, we recommend establishing standardized sampling, pretreatment, and detection and analysis methods for atmospheric microplastics, thereby laying the foundation for the construction of a monitoring system for this emerging atmospheric pollutant.