The study of ash content in raw coal is an important part of coal quality analysis. Using Series Ⅲ digital logging instrument, the author conducted log ging work along nearly one hundred boreholes in Heche coalfield of Shanxi pro vince, Yongcheng coalfield of Henan province and Huainan coalfield of Anhui province and thus acquired large quantities of initial data. This has laid a so lid foundation for the application of logging data to the study of ash content of raw coal in the coal bed. This paper describes the techniques and analyti cal results of regression analysis, one of the probability model analytical me thods.