This paper conducts an in-depth study and analysis of the flight test theories and flight techniques involved in the engine cold soak test for civil aircraft. Firstly, the paper introduces the engine cold soak test subject and its challenges. It then analyzes the single-engine gliding performance of the aircraft and investigates the engine cooling characteristics. Using big data analysis, the paper demonstrates the impact of external temperature and glide speed on engine cooling efficiency. By combining the aircraft’s gliding performance with engine cooling characteristics under different Atmospheric environment, the paper analyzes the single-engine glide method that minimizes energy loss. In the section on aircraft dive acceleration, the energy conversion modes during dive acceleration are analyzed, and key parameters affecting dive acceleration flight method are identified. Based on flight test data, detailed analyses of the flight techniques during the dive initiation phase, stable acceleration phase, and dive recovery phase are conducted. The paper examines the drag work and energy loss under different flight maneuvers and proposes optimized flight techniques and suggestions for each stage of the dive process, therefore to minimize drag work and enhance post-dive aircraft energy, thereby meeting the validation requirements of the engine cold soak flight test.