The basic knowledge of virtual reality and virtual instrument technique were introduced. According to the present safety conditions of foundation excavation, the support monitoring system of foundation excavation is put forward. With Windows and Lab VIEW technologies, the support monitoring system of foundation excavation is developed, which is integrated with data automatically collecting, information treatment, analytical evaluation, and automatically displaying the state of excavation by 3D visualization technology. Furthermore, it takes important meaning to restrict the strain, ensure the safety of the excavation and protect the surrounding environment.