Brain-computer interface technology has broad application prospect in the field of elderly care, disabled assistance, rehabilitation, hazardous environment operation, military and so on. However, the brain-computer interface technology is unable to meet the needs of practical application because of low accuracy and information transfer rate. We investigate the neural mechanisms of higher cognition of simultaneous audiovisual stimuli and ascertain neural mechanisms of modulation of spatial consistency on the processing of audiovisual information. Visual stimulus was English alphabetical and auditory stimulus was alphabetical pronunciation. Stimulus were presented in consistent and inconsistent positions. Through analysis of experimental results, it was found that the spatial consistency of stimulation affected the event-related potential component. The N1 and P2 components induced by inconsistent stimulation are significantly smaller than the consistent stimulus, but the inconsistent stimulus induces a larger P300 component. This result can improve the experimental paradigm of BCI character recognition system.