DP6 well is a long horizontal well in Daniudi gas field, its designed kickoff point was at 2510.00m depth, drilling with average building up rate of 4.85°/30m to target A in φ311.15mm borehole, and penetrating the target strata at 3033.05m depth with increasing angle to underlie coal seam. Upregulating the vertical depth of target point and sidetracking were adopted to avoid coal seam collapse. The paper analyzed sidetracking technology, selection of sidetracking point, trajectory adjusting for sidetracking, difficulties in large hole deviation sidetrack drilling and the relative technical measures; and introduced the drill assembly and construction of sidetracking.