Abstract: In order to enhance the efficient development of tight gas, Changqing Oilfield has scaled up the deployment of horizontal wells with a horizontal section over 4 000 meters. However, with the increase of horizontal section, technical challenges are encountered, including bad well trajectory control, hard sand transportation by drilling fluids, tight hole while tripping, unstable mudstone hole section, and uneasy setting of tail pipe into designed depth. Therefore, the bottom hole assembly(BHA) optimization and strength check technologies were employed to ensure a safe operation, and a environment-friendly high-performance water-based drilling fluid system combined with the borehole cleaning and monitoring technology was developed to realize the safe drilling of ultra-long horizontal sections. The casing running technology of rupture disk levitating device was applied to ensure a smooth casing operation. Furthermore, a series of specific technical measures were proposed based on the actual situation of oilfield. Therefore, the safe drilling and complement technologies for ultra-long horizontal sections of tight gas horizontal wells in Changqing Oilfield came into being. The technologies have been applied in the ultra-long horizontal sections of 3 tight gas horizontal wells in Changqing Oilfield, with successful well completion, which showed that the technologies could effectively ensure the safe construction of ultra-long horizontal sections. The successful applications show that the technologies can provide technical mothodology for efficeent development of tight gas wells in the Changqing Oilfield.