Abstract: According to the equations of atmospheric motion, the total energy per unit mass of air block under the case of unsteady and steady pressure field, two different expressions are introduced to discuss the “reference state” of moist available energy(MAE), which saves the tedious calculation of “reference pressure”. MAE is divided into two parts: “stratification component”and “baroclinic component”, and a new budget equation of MAE and its stratification component and baroclinic component is proposed. The calculation method of “stratification component of average unit mass gas block in finite gas column”, some calculation examples and the determination method of baroclinic component strength are proposed. The stratification component of MAE corresponds to the potential instability energy. The calculation shows that the stratification component is rapidly enhanced by uplift and negative pressure. The stratification component of a unit mass gas block in a finite gas column usually has a positive correlation with the convective available potential energy (CAPE), but their properties are different. From the night of 19 July 2016 to the early morning of 20 July 2016, Xingtai suffered a once-in-a-century rainstorm. The analysis shows that the largescale circulation background, the development constraints and operation of the weather scale system, favorable terrain conditions, sufficient water vapor supply and energy input contributed to the large-scale centralized release of wet effective energy, which is an important reason for the “torrential rain in Xingtai on 19 July 2016 ”.