The work aims to optimize the shape of landing buffer airbag aiming at a new type of separate flight data recording system. Based on the multi-island genetic algorithm and approximate modeling method, the optimization process was developed on ISIGHT optimization design platform and the mathematical model of the airbag buffer landing process in different falling postures was established. With electronic equipment overload as the optimization goal, the dimension parameters of the airbag were optimized to obtain the corresponding airbag shape design scheme. The approximate model describing the airbag buffer landing process had higher credibility. The multi-island genetic algorithm based on the approximate model could improve the optimization efficiency of the overall dimensions of the airbag at multiple initial fall inclination angles. Compared with the airbag model of an initial shape, the optimal airbag model calculated by the above-mentioned optimization process decreased the landing impact overload of electronic equipment at different initial fall inclination angles. The process and methods of the research have guiding significance on the design and optimization of cushioning airbag for light and small equipment.