With the increasing threat of space debris to spacecraft, it is necessary to study the de-orbit technology at the end of spacecraft life. According to the requirement of deorbiting of orbital module in the current space environment, an inflatable deorbiting sphere device is designed and analyzed. The de-orbit modeling of orbital module - deorbiting sphere system is conducted, and the atmospheric drag force of the deorbiting sphere is analyzed. The deformation of the sphere under the atmospheric drag force and air pressure is analyzed based on nonlinear finite element method, and the size and design inflation pressure of the deorbit sphere are determined. The influence mechanism of space thermal environment is studied, and a thermodynamic coupling sequence analysis framework for space inflatable structures is established. The change of gas state in the inner cavity and its influence on the configuration of the deorbiting spheres are considered. The temperature field, thermal deformation, thermal stress response and the state parameters of the gas in the cavity are obtained during the flight. The results show that the orbital module can be removed from orbit within 3 months with a 7 m sphere, and the space thermal environment has a certain influence on the configuration of the orbital diameter and the pressure in the inner cavity. The design and analysis methods in this paper provide technical support for the development of the inflatable deorbiting spheres in future.