本文在考虑灾害风险冲击的基础上,通过构建消费者—政府随机决策模型、权衡福利与财政的得失和理论推演,得到政府最优救灾规模的多维边界。具体救助规模由刻画灾害风险福利损失的各参数内生决定。具体而言,灾害损失程度是导致灾害救助需求加重的直接原因;而消费者的风险厌恶程度则会进一步扩大人们对灾害救助的需求;资本的留存情况和形成效率可减轻政府救灾的压力;灾害发生频率虽不影响最优救助规模,但会对整个社会福利产生消极影响。据此,加强灾前防御、普及灾害科普知识以及提高灾害资金运作效率,可达到减轻救助支出负担、提升灾害救助效果、增进社会的福利水平的目的。本文展示了如何设计灾害救助的最优规模,以与实际的社会环境和经济环境动态挂钩。 Based on the impact of disaster risk, this paper constructs the consumer-government stochastic decision-making model, weighs the gains and losses of welfare and finance, and deduces the theory to get the multidimensional boundary of the government’s optimal disaster relief scale. The scale of specific aid is endogenously determined by the parameters that characterize the loss of disaster risk benefits. In particular, the degree of disaster damage is the direct cause leading to the increasing demand for disaster relief; and the degree of consumer risk aversion will further increase the demand for disaster relief; the retention and formation of capital can reduce the pressure on government relief; and the disaster Although the frequency of occurrence does not affect the optimal rescue scale, it will have a negative impact on the entire social welfare. Therefore, strengthening pre-disaster defense, popularizing popular science knowledge and improving operational efficiency of disaster funds can achieve the purpose of alleviating the burden of relief expenditures, enhancing the effect of disaster relief and improving social welfare. This article shows how to design the optimal scale of disaster relief to be dynamically linked to the actual social and economic environment.