Abstract: Liquid Water Content (LWC) is a key variable of clouds and has great implication for understanding cloud microphysical processes and validating weather modification. However, the application of relationships between reflectivity (Z) and LWC proposed in previous studies is limited. In this study, the reliability of the airborne Ka-band millimeter wavelength cloud radar (Ka-band Precipitation Radar, KPR) and cloud particle detection instruments are validated first. Cloud data collected by the radar and the particle instrument onboard airplane during 2018—2020 are then processed and smoothed within different cloud diameter ranges and radar reflectivity ranges to build a new Z-LWC relationship suitable for precipitating stratiform-convective cloud. The new relationship is Z=2454.71\times \mathrmL\mathrmW\mathrmC^1.614 , with determination coefficient of 0.995 and root mean squared error (RMSE) is 0.2 g/m³. Verification shows that the retrieved LWC is consistent with the measurements by the cloud particle detection instruments, and the discrepancy between the retrieval and observations is smaller than that between retrievals by other Z-LWC relationships and observations.