The M6 coal seam in Jintai Coal Mine has complex occurrence characteristics such as roof and floor breakage， apparent dip angle controlled by double dip angle （XZ view inclination 17°， YZ view inclination 3°）， thin seam thickness （1.08~1.68m） and large variation in thickness. In the construction of directional drilling along strata， there are some problems such as difficulty of actual control， easy deviation from coal seam into unstable roof and floor， lower construction efficiency and ineffective penetration in multi-branch hole construction. Based on the calculation formula of apparent dip angle， this paper introduces the dip angle parameter of borehole along the working face to optimize the trajectory design method for the plane turning section of borehole， and carries out the verification test in Jintai Coal mine. The results show that： Compared with the original trajectory design method， the optimized trajectory design method can keep the borehole drilling along the middle of the coal seam， overcome the interference of the thickness change of the coal seam， and realize the accurate drilling along the coal seam of the plane turning section of the borehole， and the effective footage rates are 48.82%， 76.72% and 100%， respectively. The gas monitoring data of test borehole No. 8~10 show good gas extraction effect.