In view of the photoelectric system of some high-altitude fighter aircraft with high requirement of optical axis stability, several elements to improve the stability of optical axis in the design of optical system are analyzed, and the condition of heat dissipation formula is given in this paper. The formula of depth of field is deduced, and four ways to improve the stability of optical axis are obtained. The design of optical full passive compensation without heating in large temperature range, the reduction of tolerance sensitivity, the improvement of stiffness and strength of structural parts and the use of field depth focusing mechanism meet the requirements of airborne high and low space use with large working distance. In addition, the design idea of a miniaturized airborne NIR athermal zoom system is introduced. The optical compensation and four lens groups are used in the system. The last group is the depth-of-field focusing mechanism. The system has good image quality, loose tolerance characteristics and good optical axis stability in the temperature range from -55℃ to 70℃.