采用自然循环的余热排出系统是一种被动安全的系统。用一维流体动力学模型分析了具有三重自然循环回路的余热排出系统的余热排出过程，给出过程各参数的变化。分析结果表明：在余热排出过程中，反应堆冷却剂的温度和压力均存在一个最大值；这时的空冷器传热功率也达到最大值，这个最大值可以反映余热系统排热能力。 The natural circulation of waste heat removal system is a passive safety system. The one-dimensional hydrodynamic model was used to analyze the residual heat removal process of the residual heat removal system with a triple natural circulation loop, and the variation of each parameter in the process was given. The results show that there is a maximum of reactor coolant temperature and pressure during the process of waste heat removal. At this time, the heat transfer power of the air cooler reaches the maximum, which can reflect the heat rejection capacity of the waste heat system.