The invention discloses a pushing model of a steel box girder spanning an existing urban overpass and an application method thereof. The application method comprises the steps that 1, a concrete foundation is placed, and steel pipe columns are installed; 2, steel pipe column hoop fasteners are assembled into hoops to be mounted on the steel pipe columns, and then adjacent steel pipe columns are fixedly connected through horizontal connecting rods and oblique connecting rods; 3, the installation of the horizontal connecting rods and the oblique connecting rods is repeated at set interval to complete the installation of a construction platform; 4, a pushing device is installed on the construction platform, and a load dispersing device is installed above the pushing device; 5, the steel box girder is pushed to a design position through four steps of jacking, pushing, descending and returning in a walking way; 6, after the steel box girder is pushed, the pushing device and a steel supporting system are removed, and finally the concrete foundation is removed. The pushing model has the advantages that the utilization rate of lateral connecting materials of the concrete foundation and thesteel pipe columns is improved, and the possible deformation of the steel box girder is avoided by the load dispersing device.