This paper documents the third version of the GFDL cloud microphysics scheme (GFDL MP v3) used in the System for High-resolution prediction on Earth-to-Local Domains (SHiELD) model. Compared to the GFDL MP v2, the GFDL MP v3 is entirely reorganized, optimized, and modularized by functions. In addition, the particle size distribution (PSD) of all cloud categories is redefined to mimic the latest observations, and the cloud condensation nuclei (CCNs) are calculated from the MERRA2 aerosol data. The GFDL MP has been redesigned so all processes use the redefined PSD to ensure overall consistency and easily permit introductions of new PSDs and microphysical processes. Analyses gathered from simulations by SHiELD with selected configurations are examined. Compared to the GFDL MP v2, the GFDL MP v3 significantly improves the predictions of geopotential height, air temperature, and specific humidity in the Troposphere, as well as the high, middle and total cloud fractions and the liquid water path. With the more realistic PSD implemented in GFDL MP v3, the predictions of geopotential height in the Troposphere, low and total cloud fractions are further improved. Furthermore, using climatological aerosol data to calculate CCNs leads to even better predictions of geopotential height, air temperature, and specific humidity in the Troposphere, high and middle cloud fractions, as well as the liquid and ice water paths. However, the upgrade of the GFDL MP shows little impact on the precipitation prediction. Degradation due to the scheme upgrade is also addressed and discussed to guide the future GFDL MP development.