Abstract: In order to investigate the effects of task switching under different modal transitions on the attenuation phenomenon of monitor alertness, event related potential (EEG) experimental method was used to design tasks such as hazardous action recognition, hazardous scene recognition for comprehensive analysis combined with behavioral data and ERP technology; through the empirical study of the coal mine monitoring and dispatching personnel, we reveal the effect of the modal difference of switching task on the alertness of the monitoring personnel and its internal mechanism. The experiment focuses on the specific effects of task switching between different modes on the alertness of supervisors. The results show that the main reason for the decrease of work performance when switching between the same stimulus tasks is the distraction caused by the switching cost, which is reflected in the increase of the average amplitude of P300 and P200 after task switching. However, when the task was switched between different stimuli, especially when the task was switched to auditory stimuli, the participants’ alertness level was improved to some extent.