Joint three-dimensional location algorithm aims to get the north, east and height coordinates of each pixel in several adjacent Interferometric Synthetic Aperture Radar (InSAR) scenes simultaneously. Joint calibration is a key procedure to achieve an accurate three-dimensional location. It can ensure the continuity of three-dimensional location among adjacent scenes, and achieve the location of large areas with few Ground Control Points (GCPs) by using Tie Points (TPs). In this paper, a new joint calibration algorithm for airborne interferometric SAR is proposed. It calibrates north, east and height coordinates simultaneously. It employs weighted optimization method to carry out calibration, and introduces weights to calibration to discriminate GCPs and TPs with different coherences and locations. The experimental results on airborne InSAR data show that the three-dimensional location accuracy by using the proposed calibration algorithm is better than that by the traditional method.