[Objective] To study the response relationship of the biological properties of bacterial communities to long-term climate change. [Methods] The loess (YL, PL, and RL) and paleosol (YS, PS, and RS) sequences, which have persisted for approximately 500 000 years at Shimao (Y), Potou (P), and Renjiapo (R), were sampled. The structures and functions of the soil bacterial communities were predicted by bioinformatics approaches, including high-throughput sequencing and FAPROTAX. [Results] The physical and chemical characteristics associated with the loess-paleosol alternation in the three regions reflected the shifts in climatic conditions, including dry, cold, warm, and wet phases during soil development. Over this period, the climate at Renjiapo was characterized by the highest temperatures and precipitation levels, with strong influences from summer winds. Shimao experienced the driest conditions and the lowest temperatures. Potou exhibited the intermediate climatic conditions between Renjiapo and Shimao. The abundance and diversity indices of the bacterial communities in Shimao were higher than those in Potou and Renjiapo. Across all the three regions, the dominant bacterial phyla were Proteobacteria, Actinobacteria, and Acidobacteria although their relative abundance varied significantly. The bacterial communities in the loess and paleosol layers of Shimao showed greater compositional similarity, forming a network structure driven by synergistic interactions. The ecological functions of the bacterial communities in the loess-paleosol sequences were primarily associated with carbon, nitrogen, and sulfur cycling. Carbon and nitrogen cycling was weakly expressed in Shimao, while nitrogen cycling was more prominent in Potou. Renjiapo exhibited the most pronounced carbon cycling. [Conclusion] Soil bacterial communities in warm and humid climates tend to exhibit more complex network structures and greater functional diversity. In contrast, bacterial communities in dry and cold climates are characterized by similar composition and synergistic patterns, which enable these communities to adapt to harsh conditions by increasing their abundance and diversity, compensating for nutrient limitations associated with reduced carbon and nitrogen cycling.