Objective To observe the time needed for re-acclimatization in motion-sickness trainees who were in degeneration status without training for three months after acclimatization and were again trained in heat-dampness environment,so as to investigate the rules for acclimatization degeneration and re-acclimatization of motion-sickness. Methods Twenty-nine subjects with established acclimatization stopped training in heat-dampness environment for 3 months, and then they were trained again in the heat-dampness environment (39℃ and 85% humidity) by the same course and similar intensity using Criolis acceleration rotational chair. Results The time period needed for re-acclimatization was greatly shorter (19 days for 27 trainees, 2 withdrew) than the time needed for initial establishment of acclimatization (30 days) with the same level of acclimatization. Conclusion The time period needed for re-acclimatization is shorter in motion-sickness trainees who are in the degeneration status of acclimatization and receive training again in heat-dampness environment.