Based on the airborne Particle Measuring Systems (PMS), the aerosol and cloud particle observation data over Shijiazhuang during a cold-front precipitation cloud system on 4-5 October 2008 are analyzed.Results show that the aerosol distribution is obviously different before and after precipitation.Befo re precipitation, the average number concentration of aerosol is about 10³ cm^-3 with mean diameter of 0.95μm.The aerosol particles are mainly concentrated on the low troposphere below 3000 m and the aerosol concentration obviously decreases in cloud.After precipitation, the average number concentration of aerosol is about 10² cm^-3 with mean diameter of 1.28μm, and the number concentration is about one order of magnitude smaller than that before precipitation.The aerosol particles are mainly concentrated near the surface layer below 1200 m, and the number concentration decrease with height.Horizontal fluctuation of the aerosol number concentration is smaller (larger) in lower level cloud area (in no cloud area or near the surface layer below cloud area).The mean number concentration of cloud particle is one or two orders of magnitude smaller than that of aerosol.The average aerosol spectrum is bimodal and the average cloud particle spectrum is unimodal.