本文讨论了封闭简单理想气体体系,只作体积功的可逆过程。应用热力学方法导得的公式中,把难测的物理量可转变为易测的物理量(如温度、压力、体积等)来求得,反之亦然。从而使科研工作化难为易,并将测定的数值上升为理论,提高科研水平。还论证该体系,分别由热力学第一定律和第二定律开始,用热力学方法可得到殊途同归的效果,这对理论研究工作也极重要。 This article discusses the closed simple ideal gas system, only for the reversible process of volume work. In thermodynamics-derived formulas, the unpredictable physical quantities can be transformed into easily measurable physical quantities (such as temperature, pressure, volume, etc.) and vice versa. So that the research work is difficult for the easy, and the measured values ​​rose to theory, improve the level of scientific research. Also demonstrate that the system, respectively, by the first law of thermodynamics and the second law began, thermodynamics can be used to achieve the same effect of different ends, which is also very important theoretical work.