Abstract: Protection of adjacent important buildings is an essential subject during pit excavation. As for a wide foundation pit with underground garage and main buildings, the excavation and construction of main buildings may precede underground garage. In general, the underground garage is often close to main buildings, which would lead to such serious problem inevitably, the excavation of underground garage has great influence on main buildings constructed or under-construction. Based on practical engineering,finite element method is utilized to simulate this problem.