Abstract: We analyzed the composition of the soil bacterial community in two topsoil layers (0-10 cm and 10-20 cm) under three crop-forage rotation models; winter wheat-fallow-soybean (W-F-S), winter wheat-forage rapeseed-common vetch (W-R-V), and winter wheat/fallow-lucerne (W/F-L-L). The soil bacterial community was analyzed by sequencing 16S rRNA gene amplicons. The results indicated that the dominant phyla in the topsoil were Proteobacteria and Acidobacteria under all three rotation models. The dominant genera in the topsoil under the three rotation models were Rhodoplanes, Gemmata, Nitrospira, Bradyrhizobium, Adhaeribacter, and Balneimonas. The bacterial communities in the topsoil under the W-F-S rotation sequence were dominated by Janthinobacterium and Lysobacter, which were related to the prevention and control of soybean cyst nematode, and were closely associated with soil-borne pathogen resistance under the W-F-S rotation. The dominant genus in topsoil in the W-R-V rotation was Erwinia, which was related to rapeseed, and that in the W/F-L-L rotation sequence was Sphingomonas, which was indicative of no- or low-tillage during alfalfa planting. The rotations could be ranked, from highest bacterial alpha-diversity to lowest, as follows W-F-S>W/F-L-L>W-R-V in the 0-10 cm topsoil layer; and W-R-V>W/F-L-L>W-F-S in the 10-20 cm topsoil layer. This study reveals the mechanisms by which nitrogen fixation is promoted and soil-borne pathogens are inhibited in various crop-forage rotation systems, from the perspective of the bacterial community composition and function. The results of this study have important theoretical value for maintaining a healthy soil ecological environment and for establishing successful forage-crop rotation systems on the Longdong Loess Plateau.