The coastal backfill area has the characteristics of complex geological environment, thick soft layer and high groundwater level, which makes it difficult to excavate the foundation pit. Finding a safe and economical foundation pit support method is a major problem in the design of foundation pit support in coastal backfill area. Taking the foundation pit support project of Shenzhen Airport Station Comprehensive Supporting Housing Project as an example, according to the geological conditions of different regions and the requirements of subsequent construction technology, three support methods of "anchor pile + three-axis mixing pile", "double-row bored pile + three-axis mixing pile" and "composite soil nailing wall" are adopted respectively. In the process of excavation, the horizontal and vertical displacement values of the pit support structure are less than the early warning value by field monitoring and numerical model analysis. The research results show that the targeted selection of support technology according to regional segmentation in the coastal backfill area can control the deformation of the support structure within the limit range, meet the safety of the support structure, and have good economy, which can provide some guidance and reference for the excavation of deep and large foundation pits in the coastal backfill area.