Objective To compare the cognitive function changes of newly-recruited male soldiers after exposure to 3 700 m altitude for 3 months and 15 months. Methods Using "pretest-posttest design", we selected 22 newly-recruited male soldiers in this experiment, and 8 cognitive function variables, namely, the reaction and motion time, speed-perception, time-perception, depth-perception, operating-dexterity, memory span, short-term memory and attention span were analyzed by paired comparison for 3 months and 15 months. Results Compared with soldiers exposed for 3 months, those exposed for 15 months had significantly increased reaction time (P<0.05), significantly decreased operating-dexterity performance (P<0.05), and significantly improved memory (P<0.05). The depth-perception was more liable to have the "see close" phenomenon. Conclusion Compared to those exposed to high altitude environment for 3 months, newly-recruited male soldiers exposed for 15 months have a more apparent damage to the reaction time, depth-perception, operating-dexterity and attention.