Located in south Tianhuan depression in Ordos Basin, HH12P103 horizontal well is an evaluation well belonging to China Petrochemical Group North China Branch. The drilled formation is complicated with salt layer in Huanhe; sticking is easy to occur in Anding and Zhiluo group due to collapse; there is coal bed in Yan'an group; and horizontal section is in clay intercalation where collapse is easy to occur. Leakage, collapse and deviation happened during the drilling process. According to these complicated geological situation and drilling difficulties, drill string assembly was optimized, combined application of single bent-housing motor and MWD was used for anti-deviation and centralizer was used in horizontal section. Process measures were adjusted as frequently as possible with small amount for each time to ensure the smooth well trajectory. Meanwhile, mud properties were optimized timely during the drilling operation, the three-level solids control equipment was used continually and the shale shaker with 150 screens was used to clear away the harmful solids in the mud timely to ensure the hole cleaning, drag and torque reducing to improve the ROP.