Microplastics, as an emerging pollutant of global importance, have been well documented in aquatic ecosystems. However, little is known about the effects of microplastics on agroecosystems, particularly for soil microbial com- munities. Herein, microplastics collected from cotton fields in Xinjiang, China, were analysed with a scanning electron microscope (SEM) and high-throughput sequencing to investigate the attached bacterial communities. Microplastic surfaces, especially pits and flakes, were colonized by various microorganisms, suggesting active hy- drolysis of plastic debris. The bacterial communities colonizing microplastics were significantly different in struc- ture from those in the surrounding soil, plant litter and macroplastics. In addition, statistical analysis of differentially abundant OTUs showed that microplastics serve as a “special microbial accumulator” in farmland soil, enriching some taxa that degrade polyethylene, such as Actinobacteria, Bacteroidetes and Proteobacteria. Co-occurrence network analysis revealed that the biotic interactions between microorganisms on microplastics are as complex as those in soil, and Acidobacteria, Chloroflexi, Gemmatimonadetes, and Bacteroidetes are consid- ered keystone species in bacterial communities. Collectively, the findings imply that microplastics acted as a dis- tinct habitat for bacteria in farmland soil, which increases our understanding of microplastic pollution.