The egg-intima conjecture was proposed regarding the egg hot-air balloon described in Han Dynasty classics. A series of theoretical and experiment work on egg hot-air balloons were organized and carried out during teaching practice of aviation college students. It was found that hot-air could not lift the egg-intima balloons. However, it can take off under an upward hot-air flow of about 3.3 m/s. This present teaching practice, focusing on aviation history, has effectively stimulated the students' professional interest, and also exercised their innovative and practical abilities.