Abstract: The Diaokou Lobe in Yellow River Delta was formed from 1964 to 1976 under human intervention at the beginning, on which the Chengdao Oilfield, a large beach shallow-sea oil field in China, was constructed and developed. The formation and stratum structure of the lobe have a great impact on marine construction of the oil field. Therefore, the multiple historical sounding data were collected and analyzed, from which the process of estuarine oscillation and sedimentation evolution during the formation of the Diaokou Lobe were anatomized. Based on the changes in the position of the sedimentation center, the estuarine oscillation pattern of the lobe in the past was clarified. From 1964 to 1966, estuary deposits were developed in the west flank of the lobe. Under the Coriolis force, the river mouth gradually moved towards NNE and the sedimentation center moved to the east of the lobe. From 1975 to 1976, due to the instability resulted from excessive swing curvature of river channel, the river channel was cut straight artificially, and afterward the sedimentation center returned to the west side of the lobe. The lobe formation could be divided into three stages based on the accumulation rate and river mouth position: nearshore accumulation (1964—1966), overall accumulation (1966—1975), and adjusting accumulation (1975—1976). Controlled by the strong tidal flow field by the M₂ tidal point near the Yellow River Seaport, local erosion took place on the eastern flank of the Diaokou Lobe in the early and late stages of the lobe formation period, while the western flank of the lobe was the most active accumulation area in the delta during the lobe formation.