Abstract: Aiming at the stratospheric airship in the working process,a thermodynamic comprehensive model was established The influence on the internal gas temperature change by the solar radiation,ground reflection,infrared radiation,the convective heat transfer and the heat conduction were fully analyzed. The results showed that the large temperature difference of the internal gas during day and night will be a key factor affecting the performance of the long-endurance stratospheric airship. Based on this,the application of phase change materials to stratospheric airships was employed. The characteristics of phase change heat transfer problems were analyzed,and a mathematical model of phase change heat transfer for phase change heat transfer was established. To verify the accuracy of the analysis model,a ground environment test and a high altitude environment test were carried out.The experimental results are consistent with the analysis results. The results showed that the application of phase change materials to stratospheric airships can effectively reduce the daytime temperature. The results provide a new way for improving the diurnal temperature difference of the longendurance stratospheric airships.