The human brain is the most complex and efficient information processing system in nature. It can efficiently process information from multiple senses. Many studies have shown that spatial consistency of audiovisual stimuli can influence the interaction between visual and auditory stimulus, however, the multisensory mechanisms were not well understood. This study designed behavioral experiments to control the selective attention of the visual modal of the subjects, and studied the reaction time and accuracy rate of the human brain to unimodal visual/auditory stimuli and multimodal audiovisual mixed stimuli under selective attention conditions. Through analysis of experimental results, it was found that the information processing of human brain has different mechanisms under the two task conditions. When the task was spatially irrelevant, the multimodal stimuli promotes the visual discovery regardless of the position. When the task was spatially related, whether the spatial position of the auditory stimulus was consistent or not had a different influence on the visual stimulus position. Auditory stimuli that were not attended affect visual information processing, which was associated with experimental tasks. We expect that these results could helpful to process the audiovisual information of artificial intelligence.