Continuous cropping of Brassica napus impairs sustainable production via soil nutrient imbalance and microecological degradation. We evaluated rhizosphere soil properties and microbial communities under rotations crops (Triticum aestivum [TaBn], Beta vulgaris [BvBn], Glycine max [GmBn], Sorghum bicolor [SbBn], Hordeum vulgare [HvBn], and Brassica napus [BnBn]). BvBn had the highest total nitrogen, total potassium, available potassium, and organic matter contents. TaBn exhibited the highest soil enzyme activities, and its bacterial/fungal Chao1/Simpson indices and unique operational taxonomic units (OTUs; bacteria: 333, fungi: 37) exceeded other patterns. Principal coordinate analysis showed distinct microbial community separation in BvBn/TaBn versus BnBn. TaBn enriched dominant bacterial phyla Pseudomonadota and Actinomycetota; all preceding crops increased fungal phylum Ascomycota while reducing Mucoromycota. Comprehensive assessment confirmed all preceding crops, except oilseed rape altered rhizosphere microbial structure, with TaBn as the optimal preceding crops.