Abstract: With the continuous improvement of airborne POS system, UAV technology has become an important way of high precision photogrammetry. Because of the limited sampling interval of GNSS receiver in POS system, it is necessary to interpolate the three-dimensional coordinates of projection center of the airborne camera at the exposure time. Four interpolation algorithms have been studied in this paper and real measurements have been used to compare the merits and demerits of different interpolation algorithms. The results show that the root mean square error of cubic spline interpolation algorithm is better than 5 cm when the sampling interval of raw GNSS observations is more than 1 Hz, which means that cubic spline interpolation algorithm is more suitable for high-precision interpolation of threedimensional coordinates of projection center.