The precipitation on 4,5 April 2002 in Henan Province was simulated by the one-dimension stratiform cloud numerical model.The results indicate that the precipitation belongs to cold-cloud precipitation;ice-phase particles were the main components in the cold clouds both before and after the front;and the distribution of water particles from top to bottom was ice crystals,snow,cloud water,graupel and rainwater.The content and the number density of these particles in the front of the cold front were different from those behind the front,but the main microphysical mechanisms of particle formation were the same.The increasing of the numerical density of ice crystals depended mainly on nucleation and multiplication;that of snow mostly on the sublimation and accretion of ice crystals and cold cloud water;and the mass increasing of graupel on the accretion of snow and supercooled cloud water and the auto-conversion of snow.Almost all of rainwater came from graupel melting.Therefore,the mechanism of cold-front precipitation was mainly described as "vapor-snow-graupel-rain water."