Abstract: Double-step horizontal wells were drilled to develop the thin reservoirs in Harderson Oilfield of Tarim, with remarkable effects achieved.Well HD1-7H was such a well drilled in the thin reservoir, and the drilling practice provided rich experience for overcoming the difficulties for drilling the horizontal well in this area.Penetration rate was effectively improved and the reservoir was successfully drilled through.The experience obtained from this well could be used to direct the field drilling operations of such wells.