Abstract： Objective:To provide basis for preventing flight safety accidents caused by hypoxia by exploring the subjective and objective performance of pilots in hypobaric hypoxia environment.Methods:The relevant data of pilots′ high altitude physiological training were retrospectively analyzed and a symptom questionnaire upon the training were summarized. The pilots were divided into excellent group (time of useful consciousness >6 min), good group (3 min ≤time of useful consciousness <6 min) and qualified group (2 min ≤time of useful consciousness <3 min) according to the time of useful consciousness. The hypoxia symptoms and physiological parameters of pilots in each group were statistically analyzed.Results:A total of 919 pilots were included, in which 416 were in excellent group, 490 were in good group and 13 were in qualified group. Among the 25 hypoxia symptoms, there were significant differences in the components of numbness and difficulty in calculation among 3 groups ( χ2=6.04, 7.79, P=0.049, 0.020), but there were no significant differences in the components of the other 23 hypoxia symptoms (all P>0.05). The changes of blood oxygen saturation were significant in group main effect, time main effect and their interaction ( F=25.65, 1 039.77, 25.22, all P<0.001). The change of heart rate was statistically significant in the main effect of time ( F=66.41, P<0.001) but in time main effect and their interaction (both P>0.05). There was no significant difference in respiratory rate among group main effect, time main effect and their interaction (all P>0.05). The distribution and variation of blood oxygen saturation were statistically significant differences among the 3 groups in the ranges of 81%-90%, 71%-80% and 65%-70% ( H=125.93, 372.83, 13.10, all P≤0.001) unlike the range of 91%-100% ( H=2.48, P=0.289). Conclusions:The excellent group showed better blood oxygen saturation maintaining and useful consciousness time enduring capabilities, and those imply them in better performance and consciousness that enable the operation in hypoxic environment with more ease.