脱贫攻坚完成后，我国的减贫战略由扶贫转向防返贫。从减贫防贫战略的政治、经济、社会功能出发，对守住不发生规模性返贫这一底线的原因进行了系统分析。规模性返贫是自然资源环境、结构性因素和市场机制因素等风险因子叠加共振导致脱贫人群损失超载的结果，其评判标准可基于时间、空间、损失三维进行判断。将风险预防原则运用到防止规模性返贫领域，对环境层面、市场层面、主体层面的规模性返贫的潜在风险预防进行了分析。应聚焦于“帮扶机制、瞄准机制、增收机制、风险分散机制”四方面建立及时有效、动态清零、稳定可持续的规模性返贫防范机制，牢牢守住不发生规模性返贫的底线。

After the completion of poverty alleviation, China's poverty reduction strategy has shifted from poverty alleviation to poverty return prevention. Starting from the political, economic and social functions of the poverty alleviation and prevention strategies, the paper systematically analyzes the causes for holding the bottom line of ensuring no large-scale return to poverty. The large-scale return to impoverishment is the result of the loss and overload of poverty relief population caused by the superposition resonance of risk factors such as natural resources environment, structural factors and market mechanism factors, Its evaluation criteria can be based on time, space and loss. The risk prevention principle is applied to the field of preventing large-scale poverty return, and the potential risk prevention of large-scale return to poverty is analyzed at the environmental level market level and subject level. It is advisable to focus on the four aspects of "support mechanism, targeting mechanism, income increase mechanism and risk dispersion mechanism" to establish a timely, effective, dynamic, stable, sustainable and scale poverty return prevention mechanism and firmly hold the bottom line of ensuring no. large-scale return to impoverishment.

国家自然科学基金项目（71973042，71473080）；湖南省社科重点项目（21ZDB014）