本文讨论了回热式制冷机气缸与推移活塞之间的间隙C与穿梭损失、泵气损失及死隙容积损失的关系。在此基础上,从理论上证明了间隙C有最佳值,并给出最佳间隙C_(opt)的计算公式。本文对一些实例进行了计算,计算结果与实际数据基本一致。本文所提出的计算方法和公式可供设计时使用。 This paper discusses the relationship between the clearance C between shuttle cylinder and push piston and the relationship between shuttle loss, pumping loss and dead space volume loss. On this basis, it is theoretically proved that the gap C has the best value, and the formula of the optimal clearance C_ (opt) is given. In this paper, some examples are calculated, the calculation results are basically the same with the actual data. The calculation methods and formulas proposed in this paper are available for design.