The present study combined the attention network test and event-related potential approaches to investigate the neurocognitive expression of resource reduction on attention function as a result of long-term high-altitude exposure in immigrants of Tibet. When compared with low-altitude residents, the study found that high-altitude exposure decreased executive-control behavioral performance but enhanced the alerting response. Correspondingly, changes in the target N2 and P3 amplitudes indicated a decrease in conflict inhibition underlying the executive-control network. Instead, the study noted that high-altitude exposure induced additional attentional resources to the alerting stage from the aspect of a change in the cue/target N1 and P1 amplitudes, which may be derived from a reduced self-referencing function. Taken together, the current findings provided experimental evidence for the tight relationship between reduced general cognitive inhibition to the hypersensitivity of the altering attention network to external stimuli mainly observed in immigrants to Tibet.