Abstract: A deep foundation pit engineering of construction project in Kunming soft soil area may affect the stability of metro tunnel of the Line 3.On the basis of field exploration results and data analysis,using three-dimensional finite difference method,analyzing the distribution law of displacement,stress,plastic damage zone of the metro tunnel in the process of excavation unloading of the deep foundation pit.Results show that the influence of the deep foundation pit excavation on the subway tunnel is very small under the design excavation support scheme of the deep foundation pit,which conforms to the technical standards of corresponding metro structure protection,can ensure the safety use of metro tunnel.Research results provide certain reference for the engineering stability and security prevention.