Abstract: The Dongdaohaizi Sag in the Junggar Basin has a great exploration potential, but it has been less explored. In this paper, selected deep wells and newly acquired 2D and 3D seismic data within the Dongdaohaizi Sag were used to produce synthetic seismic records and perform horizon calibration, so as to identify the characteristics of seismic wave groups from medium–deep strata in the sag and clarify the exploration potential of the study area. On the basis of log characterization and synthetic seismic record calibration, four clear reflection interfaces, T₀, T₁, T₂, and T₃, were identified at the top and bottom and in the interior of the medium–deep Permian system. The characteristics of main seismic wave groups from the medium–deep strata in the sag were summarized. Specifically, T₀ is the interface between the Permian and the Carboniferous, and it is the key marker bed for regional correlation in the basin. T₁ is the interface between the Permian Jiangjunmiao Formation and the Pingdiquan Formation with source rocks developed. T₂ is the interface between the Pingdiquan Formation and the Upper Wuerhe Formation. T₃ is the interface between the Triassic and the Permian, and it represents the response of the regional unconformity between the Late Permian and the Triassic. Based on the detailed interpretation of seismic profiles, the characteristics and geological significance of seismic wave groups from the medium–deep strata in the Dongdaohaizi Sag were revealed. It is found that the seismic profile of the Upper Wuerhe Formation (between T₂ and T₃), the key target horizon, is composed of 4–6 wave peaks and troughs, with moderate continuity, as well as the transverse attenuation of the strong event energy or frequency change, which reflects the characteristics of lithologic sand bodies deposited under the background of lake transgression. The "onlapped" wave group characteristics of the Upper Wuerhe Formation in the northwestern part of the sag reflect the existence of a large provenance system, making this area a favorable target for future risk exploration.