OBJECTIVE To study EEG during simulated flight training, then to explore the situational character of mental fatigue of the pilots. METHODS Fifty male pilots were randomly choice to be recorded their EEG including rest,flight and recovery phase. Then the band waves of EEG were analysed among the three phase. RESULTS (1) During flight, the amplitude of alpha, beta, SMR, theta, gamma waves tended to increase. These changes seemed obviously in SMR, theta waves. (2) After flight, all the amplitude of the waves declined except for beta wave of the right lobe,and most of them were still higher than those before flight (P < 0.05); (3) The right brain showed a higher cerebration than the left, especially in theta wave. CONCLUSIONS Mental fatigue is started during the flight training, and the right lobe has a severe mental fatigue than the left. After flight, mental fatigue showed a slow recovery.