Abstract: Decision-making has higher requirements for the commander's mental workload, obtaining the commander's mental workload status can assist the human-computer system to improve the intelligent level of the human-machine system. In this study, a virtual unmanned aerial vehicle (UAV) operating environment is designed, and the behavioral and event-related potential changes of subjects are described by reaction time task time. Then, the less channel EEG microstate is used to evaluate the different mental workload states by tasking state EEG. Results show that the reaction time task can evaluate the mental workload state of the subjects from the behavior, and the EEG microstate can objectively evaluate the mental workload.