In this paper, the fusion data of observations collected at automatic stations in China and CMORPH (Climate Prediction Center Morphing technique for the production of global precipitation estimates) hourly precipitation at 0.1° resolution are used to identify a typical Meiyu front rainstorm, which is then simulated by WRF model. The simulation data is filtered by Barnes filtering. The energy equations are applied to analyze the filtered data for the purpose to quantitatively analyze the effects of interactions between multi-scale energy on the rainstorm intensity. The results are as follows. The simulated precipitation and its intensity are consistent with observations, which indicates that the simulation can be used in the following research. Besides, these derived energy equations can be applied to the rainstorm. The interactions between energy on the three scales involve a variety of cross scale energy interactions. During the entire rainstorm process, the baroclinic energy conversions across various scales not only include the energy conversions from available potential energy to kinetic energy, but also from kinetic energy to available potential energy. However, the baroclinic energy conversions between these scales are always unidirectional, and the value is large, that is, the strength of kinetic energy is maintained mainly by the energy transformation from the available potential energy to the kinetic energy. The baroclinic energy conversions influence the rainstorm intensity. And the baroclinic energy conversions of large scale are stronger than others in the upper and middle troposphere, while the baroclinic energy conversions of meso scale are stronger than others in the lower troposphere, especially the meso-micro-β scale. Meso-micro-β scale disturbance may be the key system that influences the intensity of rainstorm. The magnitude of wind shear affects energy conversions between different scales of kinetic energy. The magnitude of temperature or potential temperature gradient affects energy conversions between the available potential energies at various scales. The energy conversions between the available potential energy and kinetic energy are mainly related to distributions of vertical velocity and temperature of each scale. The rising of warm air and the sinking of cold air are the main processes of the conversions from available potential energy to kinetic energy at various scales.