Aiming to address the low efficiency of the traditional calibration method for star sensors, we propose a calibration method using two-dimensional (2-D) Dammann grating, which can generate a dot array with uniform intensity and a certain interval. This method is based on theoretical analysis of the diffraction angles of 2-D Dammann grating relative to the tilt angles of incident light. We calculate the angles using a fitting method and further calculate the geometric parameters, such as principal point and principal distance of the star sensor. Finally, we establish a calibration system using 2-D Dammann grating and a nanostar sensor with a 25-mm focal length and 15-deg full field of view has been calibrated. The results show that the calibration accuracy for single-star measurement is better than 6 arc sec, which satisfies the requirement for high-efficiency star sensor calibration and validates the proposed method.