Synthetic Aperture Radar (SAR) technology is a high-precision earth observation technology. In recent years, the acquisition of high-precision ground digital elevation models (DEM) based on Interferometry SAR (InSAR) technology has attracted wide attention from researchers. In this paper, a DEM extraction method is proposed for the airborne L-band repeat-pass InSAR experimental data. First, the back projection algorithm (BP) is used to obtain the master and slave images. Then, we perform interference processing and to obtain interference phase of the imaging scene. Next, the coarse-precision DEM data is used to compensate the interference phase error. Finally, the DEM extraction result of the imaging scene is obtained. The processing results of simulation and experimental data verify the effectiveness and practicability of the proposed algorithm.