Abstract: In this study, the “23·7” extreme rainstorm event in Hebei Province is selected as the research object, and correlation coefficients, multiple error indicators, and objective scoring indicators are used to comprehensively analyze the ability of the CMPAS (Chinese Meteorological Administration Multi-source Merged Precipitation Analysis System) to characterize the “23·7” extreme rainstorm using the CMPAS fusion precipitation data on ground observations in near real time. Based on the multisource precipitation analysis system (CMPAS) employed to investigate the “23·7” extreme rainstorm in Hebei Province, this study found that CMPAS fused precipitation data on the surface observation of precipitation have better characterization ability and can more accurately portray the surface and central fallout area of the storm’s precipitation intensity and extent, along with surface rainstorm. Moreover, the larger the precipitation magnitude and more centralized the fallout area, the better the portrayal effect; however, low precipitation values are overestimated, and high precipitation values are underestimated in these data. Furthermore, CMPAS fused precipitation products have better characterization ability in low-altitude and flat-terrain areas, with errors increasing with the altitude. In general, the CMPAS fused precipitation product is more accurate in characterizing the intensity and fallout zone of light to heavy rainfall, as well as the central fallout zone of rainstorms. In addition, during catastrophic weather events, CMPAS fused precipitation products can be used as an effective supplement to ground observation data where station data are sparse.