The control moment gyroscope constitutes a pivotal actuator in spacecraft attitude control systems. It dissipates heat primarily through thermal conduction and radiation into the vacuum of space, which causes substantial temperature increases that potentially compromise its stability and reliability. Consequently, analyzing the temperature field of the control moment gyroscope and ensuring its operating temperature remains within permissible limits are imperative. This research focuses on a 70 Nms single-frame control moment gyroscope. A simulation model is developed to investigate its temperature distribution and explore the influence of rotational speed, torque, and bearing preload on thermal characteristics. Upon validation against experimental data, the simulation model demonstrates an average temperature prediction accuracy of 93.87%. The outcomes reveal that temperature variations across various measurement points are sensitive to rotational speed. Notably, the lower extremity of the rotor shaft exhibits a pronounced responsiveness to torque inputs. Furthermore, both the upper and lower ends of the rotor shaft are significantly influenced by bearing preload. In particular, the maximum temperature increase of 5.2°C is observed at the lower end of the rotor shaft, while the frame experiences the least elevation of 1.72°C. The temperature field modeling approach presented herein offers valuable insights for optimizing the design of control moment gyroscopes and facilitating operational diagnostics of spacecraft systems.