Objective To investigate the effect of hypoxia on executive function of brain. Methods Oxygenblocking masks were used to simulate the oxygen state at an altitude of 5 000 meters. From January 2019 to April 2020， 40 military accompanying volunteers from the 958 Hospital of PLA were included in the study. Computer neuropsychological tests were conducted before and after hypoxia to evaluate cognitive and executive functions （including global neurocognitive index， compound memory， verbal memory， visual memory， psychomotor speed， reaction time， compound attention， cognitive flexibility， processing speed， executive function， simple attention and fine motor speed， and so on）. Each central nervous system test includes seven parts： word memory， visual picture memory， finger continuous tapping， digit symbol coding， Stroop test， continuous performance and shift attention test. The Go / NoGo paradigm task functional magnetic resonance imaging （MRI） data was used. Local consistency analysis method was used to analyze the differences of brain executive function between normoxia and hypoxia. Results Under hypoxic conditions， the scores of neurocognitive domain were significantly lower than those under normoxic condition， including overall neurocognitive index ［（95.54±6.59） vs（ 100.75±7.08）］， complex memory［ （92.15±10.23） vs（ 98.35±8.16）］， verbal memory ［（92.56±9.51） vs（ 99.46±6.42）］， psychomotor speed［ （109.63±6.64） vs（ 119.36±16.78）］， reaction time ［（89.87±9.09） vs（ 98.63±6.37）］， processing speed［ （112.67±14.35） vs（ 131.78±14.53）］， executive function ［（106.43±11.75） vs（ 115.33±10.82）］. The differences were statistically significant（ all P ＜ 0.05）. The response accuracy rate of Go/NoGo task under hypoxic condition was lower than that under normoxic condition ［（83.85±7.74）% vs（ 89.9±6.01）%， t=-4.27，P ＜ 0.01］， and the reaction time of keys was increased ［（1 049.28±171.28） ms vs（ 957.08±178.14） ms； t=2.32，P=0.025］. The local consistency values of left inferior temporal gyrus（ 0.516±0.045）， middle temporal gyrus（ 0.534±0.064）， parahippocampal gyrus（ 0.519±0.046） and right inferior temporal gyrus（ 0.549±0.056） were higher than those under normoxic condition； The local consistency values of left superior temporal gyrus（ 0.411±0.048）， inferior frontal gyrus（ 0.478±0.049）， angular gyrus（ 0.503±0.063）， superior parietal lobule（ 0.512±0.070）， right fusiform gyrus（ 0.461±0.044）， superior temporal gyrus（ 0.455±0.046）， and anterior cingulate gyrus（ 0.494±0.049） were lower than those under normoxic condition. The differences were statistically significant（ all P＜0.05）. Conclusions Hypoxia affects the function of multiple brain regions， which are related to executive control， resulting in decrease of brain tasks performance.