Huagang Formation in offshore A gas field is a large composite channel deposit with horizontal migration and vertical su‐perposition of channels. The target layer has a large burial depth，few drilled wells，and poor-quality seismic data. It is difficult to identify the channel sand bodies based on seismic data，and the development accuracy requirements are not supported. Based on the classic channel deposit styles and the characteristics of drilled wells，the seismic responses of different channel deposit styles were clarified by forward modeling technology. On this basis，the composite channel zones were characterized by using strata slice tech‐nology，and single channel boundaries were accurately tracked by combining near-angle stacked data volume and far-angle stacked data volume. The Poisson impedance inversion was selected to predict the dominant sand bodies in channels quantitatively. Finally，the seismic comprehensive characterization technology was formed for the internal structures of deep single channels with few wells and stepwise constraints. Based on the characterization results，four wells were deployed in the dominant sand bodies of different channels. The actual drilling confirmed that there were different gas-water interfaces in different channels，indicating that lithologicstructural gas reservoirs formed by multiple channels were developed and have different gas-water systems，which confirmed the re‐liability of single channel characterization. All four wells have achieved an average high gas yield of 20×10⁴ m³/d after production，which further confirmed the accuracy of dominant sand body characterization. This method strongly supports the development and adjustment of the gas field，and the geological reserves and daily gas production of natural gas have achieved breakthroughs.