To further investigate the dominant microphysical process, the evolution of the vertical structure of polarimetric variables is fully illustrated. Corresponding microphysical processes is identified using the polarimetric radar fingerprint of the vertical profiles of horizontal polarization ZH, differential reflectivity ZDR, and the specific differential phase KDP. Results show that complex cold processes are involved above the freezing level, while only the coalescence and/or accretion processes are active below freezing level during the evolution of the rainband. Further combining the polarimetric fingerprint and the vertical water vapor profile estimated from ZH and ZDR, results indicate that the conversion of cloud water into rainwater through cloud water accretion by raindrops dominates the heavy rainfall, while the ice particles generated by the cold processes play an important roll in accelerating the accretion process. The precipitation efficiency is, for the first time, estimated from the observations for the typhoon system. The precipitation efficiency over 60% suggests the accretion of cloud water is an important mechanism to produce heavy rainfall.