Abstract: It is significant to calibrate interferometric parameters of dual-antenna airborne InSAR（Interferometric Synthetic Aperture Radar）systems for deriving accurate DEM (Digital Elevation Model) with large areas. A new outside calibration model considering phase offset, baseline length and baseline angle was proposed in order to calibrate interferometric parameters effectively, which was induced from the basic theory of DEM deriving from InSAR. And its solution scheme was designed. The outside calibration experiments were done with height control points measured by GPS to calibrate the dual-antenna airborne InSAR system researched independently by Institute of Electronics, Chinese Academy of Sciences. The accuracy of heights derived with calibrated interferometric parameters was calculated, as validated the proposed calibration model and its solution algorithm.