Abstract: Aryskum oilfield is a complicated oil and gas reservoir with large gas cap, thin oil rim and edge/bottom water. To determine the rational development method for this reservoir, based on extensive investigations of development methods for analogous reservoirs both at home and abroad, the author adopted the method of gas injection into the gas cap and barrier waterflooding to avoid gas channeling and water encroachment. Horizontal well was adopted to develop the thin oil rims and the well patterns were perfected for progressive and extensional development in the south and north of the oilfield. After implementation, the gas channeling in the gas cap has been effectively controlled and the formation pressure has been maintained and kept rising steadily, while the oil production of the oilfield increased year by year. Therefore, the method has been determined as the effective development method for such complicated oil and gas reservoirs