Research of particles from cloud to rain is a fundamental approach to study the precipitation mechanism.Based on the cloud radar and dual-polarization precipitation radar data,this paper analyzes the echo characteristics and formation of a typical convective warm cloud precipitation process in Nanjing on August 9,2020.Using various radar parameters and fuzzy logic algorithm to identify the hydrometeor types,the evolution of hydrometeors in precipitation process is analyzed.Results show that the cloud with high precipitation efficiency behaves approximately a tropical structure with strong and low echo centricity.When the radar observes large spectrum width and linear depolarization ratio,strong updraft in the upper cloud and positive-negative velocity presenting vortex convergence,it indicates that heavy precipitation is about to occur.The precipitation particles identified by the fuzzy logic algorithm are mainly raindrops,with wet and dry snow particles at the top of the cloud.With a large number of cloud and precipitation particles in different sizes and complex orientations,the collision-coalescence process,as the main precipitation mechanism,is quickly completed under the action of the rising air flow and vortex convergence.