An modeling and optimal design method of stratospheric airship propulsion system based on energy balance was proposed to achieve both high efficiency and light weight goals.Efficiency and weight surrogate models of motor and propeller were individually established using design of experiments method and surrogate model technology. A weight calculation model for airship energy system containing solar cells and energy storage batteries was also built. Based on the multi-island genetic algorithm

the optimal design model of airship propulsion system was established with the energy and thrust balance as the constraints

and the minimum total weight of the propulsion and energy system as the goal. Optimization design of an example was carried out. The results show that the efficiency of the optimized propulsion system is increased by 23%

and the total weight of the propulsion and energy system is reduced by 340 kg

verifying the feasibility and application value of the modeling and optimal design method of stratospheric airship propulsion system.