Yellow River Delta undergoes intensive conversion from natural wetland to agricultural fields and artificial woodland. In this study, we analysed how the conversion affects bacterial community diversity and composition by Illumina Miseq sequencing combined with functional prediction. Compared to natural wetland, arable land and woodland were featured with higher soil organic matter, total nitrogen and bacterial diversity, but lower electrical conductivity. The bacteria Gemmatimonadetes related to soil organic matter and total nitrogen, was enriched in arable land, while salt-resistant bacteria (e.g. phylum Chloroflexi and its class Ardenticatenia) were abundant in natural wetland. Moreover, the relative abundances of the nitrifying bacteria Nitrospira and Nitrosospira were significantly higher in arable land and woodland than in natural wetland, suggesting that land use changes significantly affect the bacterial processes involved in nitrogen cycling. Redundancy analysis (RDA) showed that the differences in bacterial community were attributed to soil nutrient-related properties (i.e., total nitrogen and soil organic matter), soil salinity (i.e., electrical conductivity), and heavy metals (i.e. Cu and Cr). PICRUSt results revealed that land use conversion from natural wetland to arable land increased soil functions, e.g., biosynthesis process and oxidative phosphorylation. The data help us elucidate how land use changes affect terrestrial ecosystem function, and advise local farmers to apply the suitable land-use strategies and keep agricultural sustainable development.