Abstract: A new method for the in-flight calibration of camera's intersection angle was put forward. It is different from the photogrammetric resection which is widely used at present. Take the three-line-array CCD surveying and mapping camera as example, through the analysis of its working principle, the geometric model to calculate the camera's intersection angle was established, and the correlative experiment using the image data of TH satellite was carried out. Result shows that this method is feasible, and the outcome is very close to the conclusion got by the photogrammetric method. Meanwhile, the affection of the orbit determination precision and the ground control points' precision on the camera's intersection angle was calculated and analyzed. Compared with the photogrammetric method, it is easier to understand, and can further be used to calibrate the off-axis angle of the multispectral camera and high definition camera in-flight. It is of great significance.