Abstract: Based on an old excavation deepening project with complex boundary conditions in Guangzhou, a combined scheme of composite soil-nailing wall and pile-anchor retaining structure scheme is selected. The reasonable pile spacing and pile waterproof curtain and other measures are adopted to ensure the safety of excavation and the surrounding environment as well as its smooth constrcution. The monitoring data and the deformation characteristics of the retaining structure show that the combined support achieves satisfactory effectiveness.