The accurate prediction of the number of summer precipitation days has important practical significance for industries such as agriculture,transportation,and electric power supply.The data of summer precipitation during 1951-2012 provided by Lianyungang Meteorological Bureau were used to analyze the interannual characteristics of summer precipitation days,yet no obvious temporal variation trends were found.Thus a model to predict the regularity of precipitation days is established based on analysis of climate factors listed by National Climate Center website,and CART decision tree algorithm.Year with positive/negative anomalies of summer precipitation days in Lianyungang is defined by various climatic factors,which is trained by sample data of 52 years with training accuracy of 90.38%/86.54%.The remaining data of 10 years are used to test the model,resulting in accuracy of 80% for positive/negative anomalies of summer precipitation days prediction.The rule set is provided for meteorological business and decision-making.