Composition of renewable power system for stratospheric airships is introduced, curved paving model of solar array is established, the high accuracy calculation method for output power of solar array is proposed, and operation process of renewable power system is simulated. On basis of this, endurance of the stratospheric airship is evaluated, and the influence of some important factors on endurance is analyzed, including wind resistance strategy, photoelectric transformation efficiency of solar array and the specific energy of lithium battery. Simulation results show that, 1) endurance of the stratospheric airship can be improved by adjusting power sequential during day and night with maneuverable wind resistance strategy, for the case in this paper, endurance increases 24.2 h compared with fixed point wind resistance strategy, 2) endurance can be greatly improved in a certain range through increasing photoelectric transformation efficiency of solar array and the specific energy of lithium battery, for cases in this paper, endurance increases 73.5 h and 47.5 h respectively, 3) to realize closed cycle of renewable power system during day and night, attenuation of radiation flux with the change of date must be considered in design of renewable power system, and sufficient redundancy should be designed for solar array.