Increasing the length of coal-bearing interval of through beds hole in soft coal seam coal can improve gas drainage effect of single hole, which can be realized by using the flexible drilling assembly. This paper presents the mechanical model of flexible drilling tools construction, makes the studies on the kinematics characteristics of strong deflection and puts forward the kinematics curve. According to the above, the strong deflecting drilling technology is researched to increase drilling rate in coal seam as far as possible.