The environmental and engineering safety and construction quality control during foundation pit construction should be guaranteed. As a result, a design and construction method for open excavation technology under complex conditions, i.e. strong retaining, precise water control, fast excavation, early support, fast face closure, frequent measurement and less disturbance, is proposed considering soft strata, rich water and complex surrounding environment. The details of the method include: (1) The retaining structure should be rationally designed, and the construction quality should be strengthened. (2) The groundwater should be precisely controlled, including precise design of water control schemes, strengthening the construction quality of water control measures and informatized construction. (3) The foundation pit should be rapidly excavated to reduce impact on the surrounding environment. (4) The support should be erected in time to reduce ground settlement. (5) The excavation face should be rapidly closed and the structural base should be quickly constructed after the foundation pit is excavated to the bottom. (6) The monitoring and measurement should be strengthened during the excavation and support of foundation pit, and timely data collection, data analysis and feedback should be carried out to guide the construction. (7) The disturbance of ground on foundation pit should be reduced by adopting proper measures. The results can provide reference for design and construction of opencut foundation pits in the future.