Based on the excavation engineering of national large scientific project Five hundred meters Aperture Spherical Telescope(FAST), through location optimization of the excavation center,dangerous rock pile of governance,high and steep slope protection,depression drainage and ecological environment protection and so on, the key technology of Karst depressions excavation and design had been discussed, the corresponding measures and solutions had been proposed, ensuring the smooth completion of the engineering. The research provides reference for the excavation engineering under similar engineering environment.