Abstract: In view of the low drilling efficiency and the difficulty in obtaining formation stress during the drilling process of rock formation, the drilling process was decomposed into two steps: axial compression into rock mass and rotational cutting rock mass, the static relationship of cutting rock mass rotary cut by cutting edge was analyzed, the static model of rotational cutting was constructed.The influence law of cutting depth, cutting edge shape and rock mass mechanical property on cutting force was obtained.The results show that there is a linear relationship between cutting depth and cutting force, the greater the cutting depth, the greater the cutting force; the cutting force increases first and then decreases with the increase of cutting edge angle; rock cohesion, internal friction angle is linear with the cutting force, the greater the cohesion and internal friction angle, the greater the cutting force required.