Aviation camera is a kind of airborne optical instrument,which acquire the targets on ground through shooting ground sceneries. For meeting the requirements of long range shooting,long focal length object lens is needed to obtain bigger size images of the objects far away in image plane. A long focal length aviation camera optical system is designed at focal length 550 mm,F number 6 with field 2ω=9°. Double Gauss object lens is selected as an initial structure in the design of the object lens of the long focal length aviation camera. The system is optimized by ZEMAX to improve image quality. The optimized system is standardized and performed tolerance analysis to obtain the needed optical system. The system has good image quality under 80 pairs per millimeter spatial frequency and MTF is more than 0.15.