Although the physical quantity of enthalpy is used frequently in natural sciences and technical sciences, its physical meaning is ambiguous for quite a long time. In this paper, the author treats of the mistakes concerning this concept in the thermodynamics texts and references and points out that the physical meaning of pv is the potential energy of pressure along the path lines in the flowfield when the field of pressure is steady(namely). Also, this physical meaning of enthalpy is suitable for closed system under the condition of quasi-static process with constant pressure.