Coordinate data, as the basis of the data involved in the whole process of airborne geophysical data processing, are closely related to the quality of data processing and interpretation effects. Based on an analysis of the requirements of geophysical data processing and interpretation system and the employment of C++ language, in combination with the coordinate parameter file management mode, the authors provided the standardized API interface, developed the function of coordinate transformation, and evaluated the conversion accuracy. The results have achieved the requirement of airborne geophysical data processing.