Airborne Ka-band InSAR system is able to provide images with high resolution, high signal-noise-ratio, high-precision attitude, and high-precision positioning data, thus DEM with high-precision can be obtained using InSAR. In this paper, we use the orthogonal decomposition of look vector to analyze the three-dimensional positioning model based on the airborne Ka-band imaging geometry, then establish the interferometric calibration model to correct the main error sources. Besides, we implement multi-baseline fusion given that the airborne instrument consists of three antennas, which make it possible to construct three interferograms through one flight. We conduct experiments using airborne Ka-band InSAR data covering Xi’an, China. Finally, we use ground control points (GCPs) for the interferometric calibration model and generate the fused DEM. Experiments show that we can determine the airborne Ka-band InSAR system parameters accurately using interferometric calibration model. The vertical accuracy of multi-baseline fused DEM is 0.33 m, and the plane positioning error is 1.40 m. It meets the requirements of DEM quality at 1:5000 measurement scale.
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