Long-term climatic differences shape the ecological memory of soil bacterial communities, which refers to the ability of past events to influence current environmental responses. However, their ecological mechanisms and consequences for bacterial responses to current environmental changes remain largely unknown, particularly in terms of temporal dynamics. Therefore, soil bacterial communities in the arid (Lhasa River Basin) and humid (Nyang River Basin) grasslands of the Qinghai-Tibet Plateau were compared to explore their temporal dynamics in response to current soil moisture and the resulting ecological consequences. Our results indicate that the differences between current and historical soil moisture determine the degree of divergence in bacterial community composition and potential function. The temporal dynamics of bacterial community composition, life strategies, and potential functions differed with environmental history, even under comparable moisture conditions. In contrast, bacterial communities with the same environmental history exhibited similar temporal dynamics, suggesting that environmental history has an important influence on bacterial community dynamics. This phenomenon may be caused by the continuous accumulation of bacterial community life strategies as an informational legacy, regulating future response patterns to soil moisture changes and thereby affecting biogeochemical cycles in the soil. For example, soil bacterial communities in relatively arid regions may increase their potential for dormancy, even when the current soil environment is moist, thereby enhancing ecosystem resilience by improving their capacity to respond to future drought events. This study provides new insights into the ecological memory of soil bacteria, emphasizing its critical role in influencing the compositional and functional changes of bacterial communities in response to current environmental changes. It highlights the significance of understanding the effect of environmental history in predicting the future responses of bacterial communities to disturbances and environmental changes.