Abstract: According to precipitation observations from the national reference station, ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5) data, and the WRF (Weather Research and Forecasting) mesoscale numerical model, this study aims to examine the water vapor transport, budget, and the influence of Taihang Mountain topography on the extreme precipitation process that occurred in central Hebei during the “23·7” extreme precipitation event. The results indicate the following: 1) Following the westward extension of the strong subtropical high, a “high-pressure dam” was formed in conjunction with the continental high, effectively blocking the northward movement of the weakened Typhoon “Du Suri.” This, combined with the eastward movement of typhoon “Kanu” in the Northwest Pacific, established two water vapor channels (spanning 1000–700 hPa). One of these channels is the West Pacific water vapor channel, with water vapor mainly concentrated at 1000–900 hPa. The other channel is the South China Sea water vapor channel, with water vapor mainly concentrated at 850–900 hPa. 2) The main water vapor input boundaries in central Hebei are the southern and eastern boundaries, of which the southern boundary is the main boundary. The main water vapor output boundaries are the northern and western boundaries. A positive correlation is observed between hourly precipitation and the net water vapor flux budget in central Hebei. The net water vapor flux budget in central Hebei on 30 July was approximately 4.7 times that on 29 and 31 July 2023, providing favorable conditions for the occurrence and development of extreme precipitation. 3) The topography of the Taihang Mountains considerably influences the area and intensity of the rainstorm. Blocked by the northern Taihang Mountains, long-distance water vapor transport accumulates in the piedmont and the piedmont plain. From the surface to 700 hPa, the northeasterly/easterly winds are forced to ascend in front of the mountain, resulting in a stable convergence of southeast and northeast winds in the piedmont plain. This convergence facilitates a sustained and strong vertical upward movement from the piedmont to the piedmont plain. This robust and deep water vapor convergence, combined with vertical transport, contributes to the occurrence of intense precipitation in the piedmont and the piedmont plain.