A new coupling thermodynamics analysis method based on the ADAMS and MATLAB joint simulation was proposed for ascent stage of stratospheric airship in complex external environment and multi-physical coupling conditions. An accurate thermal-mechanical coupling mathematical model for ascent of airship was built by using MATLAB in this method. Based on this method, the discrete time-domain method and Newton iterative algorithm were used to decouple the model to obtain relevant parameter curves. The model of airship was established in dynamic environment of ADAMS and a CONSUB subroutine which is available to retrieve the variable data of the airship mass in real time was developed. The visualized simulation control for the ascent stage of variable mass stratospheric airship was realized by applying the decoupled load and calling the subroutine. The coupling thermodyna-mics analysis of a certain stratospheric airship was performed using the above method to obtain the rules of trajectory, attitude and air temperature in air bag. The results show that the design minimum of the pressure difference between the inside and outside of the airbag is not significant for real-time control of airship speed, and the temperature of gas in the air bag rises during the stratosphere stage. The analysis indicates that this method can efficiently and accurately simulate the ascent of stratospheric airship with variable mass under the coupling of complex multi-physical conditions and obtain thermodynamic parameters. This method is of great reference value for the parameter control and optimization design of airship.