The Beijing-Tianjin-Hebei (BTH) region experienced a long time of rainstorm from 27 July to 1 August 2023. A basin-wide catastrophic flood occurred in the Hai River Basin. It was the peak period of rainstorm from the night of 29 to the daytime of 30 July, and extremely heavy rainstorm was observed in southern and central Hebei in turn. The dynamic and thermal characteristics of the rainstorm are studied by using black body temperature (TBB) of FY-4A, conventional observations and the Final Analysis (FNL) data from the National Centers for Environmental Prediction (NCEP). The results are as follows. (1) The long-term transport of warm and moist air by the low-level jet of the southeast wind in the periphery of the tropical cyclones is a prerequisite for the maintainence of the rainstorm. The rainstorm centers appear on the windward slopes of mountains and the piedmont plains, where the terrain mainly enhances the upward motion by forcing the warm and moist air to rise. (2) During the rainstorm process, the entrance region of the upper-level westerly jet shifts eastward from southern Mongolia, and the exit region of the low-level southeasterly jet advances northward from Hangzhou Bay and extends westward. The strengthening of the northward-sloping updraft in the BTH region is also clearly related to the coupling between the upper-and low-level jets. During the peak period of the rainstorm, the western edge of the upper-level jet entrance remains relatively stable, while its southern boundary shifts northward in synchronization with the exit region of the low-level jet, and the rainstorm center is located in the coupling region of the upper-and low-level jets. (3) From the night of 29 to the night of 30 July, the maximum values of both heating and drying rates over the major rainstorm area appear in the lower troposphere ( about 800 hPa ). The release of latent heat caused by the condensation of low-level water vapor is an important thermodynamic phenomenon during the peak period of heavy rainfall in the BTH region.