Farmland mulching can maintain soil temperature and moisture, increase crop yields, which plays a positive role in agricultural planting in the arid area. However, the composition of the soil microbial community and the carbon cycle involved is not well understood under the ground cover scenario. Based on the Changwu Agro-Ecological Experiment Station, this study set up a long-term positioning Experiment to explore the impact of long-term land cover pattern on soil bacterial community structure and carbon metabolism capacity. In this study, we include five treatments: control uncovered (CK), plastic film mulching (F), high amount of straw mulching is carried out in July, August and September every year (St90), low amount of straw mulch throughout the growth period (S45), high amount of straw cover throughout the growth period (S90). We combined Illumina MiSeq sequencing and Biolog-ECO technology to analyze the functional characterization of soil bacterial community composition in terms of carbon source metabolism. The results indicated that the soil bacteria showed high degree of epistatic clustering after mulching treatments, and the operational taxonomic units (OTU) numbers of soil bacteria under different treatments decrease as St90, S45, F, CK, S90. Redundancy analysis (RDA) showed that AP, NH4+-N, MC were the main environmental factors affecting bacterial community composition. Proteobacteria, Acidobacteria and Actinobacteria are the main dominant flora in this area. Long-term surface cover resulted in significant differences in soil bacterial carbon metabolism, which was highest in the F treatment. Structural equation modeling (SEM) shows that surface cover has direct and indirect effects on bacterial carbon metabolism capacity and diversity through soil physicochemical properties. Reasonable mulching patterns can greatly change the community structure and carbon metabolism of soil bacteria, and play a positive role in the sustainable development of agro-ecosystems in arid area.