Abstract: For the problem that lacking the theoretical guidance of feeding force parameters during deep-hole directional drilling in coal mine affects the borehole trajectory, drilling efficiency and hole forming rate, we propose the determination method of feed force parameter by combining theory and practice. Based on reasonable hypothesis of drill pipe stress process, we establish equilibrium equation of lifting force and feeding force in the drilling process from the perspective of statics. According to the measured data in field, we calculate coefficient of frictional resistance and minimum breaking strength of rock, and determine the minimum feed force equation of drilling in different lithology. At last, through comparing the theoretical calculation value and field measured value of drilling, we prove that the theory of feed force parameter is feasibility and rationality.