Abstract： Objective:To help flying personnel prevent flight fatigue risk and ensure flight safety by investigating the fatigue and countermeasures of flying personnel during long-haul flight.Methods:Air Force flying personnel were randomly selected from a cluster. They were divided into 21-30, 31-40 and 41-50 years group according to age. According to the post, they were divided into fighter pilots, bomber pilots, air navigation commander/air communication controller/aerial machinist and other groups. The self-made "questionnaire of aeromedical support to long-haul flight safety" was used to collect the fatigue condition and countermeasures of flying personnel in long-haul flight for the comparison among age and post groups.Results:Out of 156 questionnaires, 150 were valid, with a response rate of 96.2%. For the comparisons among age groups, the significant differences were observed in 3 fatigue symptoms such as drowsiness/sleepiness, discomfort on neck, waist, and shoulders, and degraded reaction ( χ2=12.62, 11.77, 12.23, P=0.002, 0.003, 0.002), 2 fatigue countermeasures such as talking with teammates and engaging in physical activity ( χ2=6.37, 16.70, P=0.041,<0.001), and 4 measures of maintaining flight ability such as sleep management, comprehensive physical training, functional food intake and simulation training ( χ2=8.81, 11.48, 9.59, 7.32, P=0.012, 0.003, 0.008, 0.026). For the comparisons among post groups, the significant differences were observed in 3 fatigue symptoms as visual fatigue, drowsiness/sleepiness, and discomfort on neck, waist, and shoulders ( χ2=10.39, 17.89, 8.42, P=0.016, 0.001, 0.038), as well as in fatigue countermeasures chosen like taking in water or food ( χ2=19.06, P<0.001) and in improving flight ability chosen like relieving eye fatigue ( χ2=12.09, P=0.007). Conclusions:The age and post factors influence the fatigue conditions and countermeasures chosen in the flying personnel during long-haul flight. The targeted and comprehensive interventions are suggested.