Abstract: The changing climate has increased the frequency of hazardous weather events, which has placed high demands on monitoring hazardous weather. In addition to the conventional S- and C-band operational radar networks, in recent years, many cities in China have built X-band weather radar monitoring networks to improve the spatiotemporal resolution of hazardous weather monitoring and the low-level observation information of weather systems. The hybrid-tilt reflectivity is extracted from the multi-tilt radar measurements over the radar domain, which is closest to the surface and unaffected by blockage due to terrain or surface features. This reflectivity is important for monitoring the occurrence and development of convective systems. To take advantage of the wide detection range of S- or C-band weather radars and the high spatiotemporal resolution of X-band weather radars, this study presents a method for mosaicking hybrid-tilt radar reflectivities derived from the measurements of S- or C-band and X-band weather radars. This method involves (1) generating hybrid-tilt reflectivity, (2) converting radar reflectivity across different frequencies, and (3) mosaicking reflectivity measurements from multiple radars. Based on this method, the hybrid-tilt reflectivity mosaic products for Shenzhen and Xi’an are generated, which have spatial and temporal resolutions of 30 m and 1 min, respectively. These products are evaluated during different types of precipitation events using the reflectivity data from the Dual-frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) core observatory (GPM-DPR). Results show that the hybrid-tilt reflectivity mosaic products are highly consistent with the GPM-DPR reflectivity measurements, with mean errors being within ±1 dB.