Based on weather charts,satellite data,surface precipitation data,GPS,specially the Particle Measuring System(PMS) data,etc,obtained in the cold vortex system in North China,in May 17—18,1999,some features for this type of system were concluded as the fowlloing.①The precipitation process was due to the meeting of the Huabei cold vortex and the shear line system along the Changjiang River.②The precipitation clouds can be divided into two layers,and there is a dry layer among them.In the cloud body,the supercooled water content is low(0.035g/m³),and its distribution is not even.Due to the existence of the dry layer,the rain droplets evaporate after leaving the clouds.③The maximum cloud particle concentration is 250/cm³.The cloud particle diameter and concentration are not uniform in the cloud.