鸟类是脊椎动物中适应飞行的类群，而飞行是一种高能耗的运动，因此鸟类需有更高的呼吸与代谢效率。为适应飞行生活，鸟类进化出了一套独特且高效的呼吸系统，其呼吸系统结构、机制与其他陆生脊椎动物(特别是哺乳类)存在明显差异：通过气囊辅助肺进行双重呼吸，在呼吸过程中形成了气体的逆流交换系统。本文对鸟类呼吸系统结构、影响鸟类呼吸效率的因素进行了总结；同时针对鸟类呼吸过程的逆流交换机制进行数学建模，并给出数值解求法。本研究从结构与机制两方面对鸟类的呼吸机制开展探讨，以增进对鸟类呼吸高效性的了解。

Birds are a group of vertebrates that adapt to flight, which is high-energy consuming and require matched respiratory and metabolic efficiency. In order to adapt to flight life, birds have evolved an exceptionally efficient respiratory system, whose structure and mechanism are significantly different from those of other terrestrial vertebrates (especially mammals): they perform dual respiration through air sacs assisted lungs, forming a counter-current exchange mechanism during respiration. Here, the structure of avian respiratory system and the factors affecting the efficiency of avian respiration were summarized in detail. The counter-current exchange mechanism of bird respiration process was modeled and the numerical solution was given. This study explores birds respiratory mechanisms from both structural and mechanistic, in order to enhance understanding the high efficiency of birds respiratory.