The Interferometric Synthetic Aperture Radar (InSAR) technology has developed rapidly and is being applied in various surface monitoring fields. However, in the monitoring of mining subsidence, there are problems such as insufficient number of monitoring points, inaccurate selection of points, and incorrect monitoring of large gradient deformation areas. The Unmanned Aerial Vehicle (UAV) photogrammetry, as an advanced technology, has been widely used in the field of mining subsidence monitoring in recent years. It has the characteristics of low cost, high point density, multiple products but insufficient monitoring cycle, and poor accuracy in monitoring small deformations. Based on this, this article combines the advantages of UAV photogrammetry products and gradually solves the technical defects of InSAR to explore a mining area subsidence monitoring method that can monitor higher accuracy, reliability, and completeness. The study is conducted using a mining area in Inner Mongolia Province as an experimental area, combined with Sentinel-1A data from June 11, 2018 to October 21, 2018 and field observation station data. The contents and results are: (1) By utilizing the advantages of high accuracy and low cost of UAV Digital Elevation Model (UAV DEM), the UAV DEM of local mining area was fused with a large-scale Shuttle Radar Topography Mission DEM (SRTM DEM). The 20m contour lines in the fused DEM were smooth and without truncation, indicating a good fusion effect; (2) In response to the issue of insufficient accuracy of external DEM, the fused DEM was used as an external reference DEM to participate in data calculation. The obtained Small Baseline Subset (SBAS) and Distributed Scatterers InSAR (DS-InSAR) mining subsidence monitoring results improved the monitoring accuracy by 2.5mm and 1.5mm compared to the original DEM, respectively; (3) In response to the insufficient number of monitoring points in SBAS-InSAR technology and the problem of selecting points in conventional DS-InSAR, we combined UAV Digital Orthophoto Map (UAV DOM) to refine Distributed Scatterers Candidates (DSCs) and eliminate low monitoring accuracy DSCs. While retaining the number and density of points, it could make the selection of DSs more accurate and reliable; (4) Due to the large deformation gradient in some areas of the mining area, there are still monitoring errors in the refined DS-InSAR subsidence result. We used the method of deformation result fusion to fuse UAV subsidence basin with InSAR subsidence result, which could to some extent compensate for the shortcomings of InSAR technology in monitoring large gradient deformation areas and obtain more complete mining subsidence basin, but there are obvious fusion boundaries.