There was a widely precipitation on April 4-5,2002 in Henan Province.The features of the stratiform cloud system and its precipitation characteristics in a cold front are analyzed by using the intensified sounding and radar observational data,and the satellite pictures,etc.The result show that the precipitation results from the atmospheric potential instability between 700hPa and 500hPa,and the area of atmospheric potential instability (∂θ_se/∂z<0) corresponds to the maximum value center of surface precipitation fairly well.At the same time,a jet streamcore existing in 250~200hPa occurs before and after the formation of the atmospheric potential instability,and there is a wind direction shear above and below the potential instability layer.Small cloud depth,low cloud top height,inhomogeneous structure are the main characteristics of the precipitation cloud.Weak potential instability in 700~500hPa,small quantity of vapor transfer and low cloud top temperature are the main reasons for small precipitation in this precipitation process.