Abstract: The drillability of rock is a collecting index to evaluate the fragmentation rate of rock,so the drillablilty is an im- portant basis for the selection of drilling bit.However.the present available drillability section can only provide one curve or a certain curved surface,so the narrow application range is hard to meet the requirement of practice.On the ba- sis of analysis on sliding least square method,the calculation of distribution pattern of three-dimensional drillability field is deeply discussed and analyzed,and a theoretical model and calculation method of regional drillability is obtained.Practi- cal application shows that the precision of this mathematical model is high enough to meet the requirement of project.