Event-related potential (ERP) is a basic,non-invasive method of electrophysiological investigation. It can be used to assess aspects of human cognitive information processing. Recordings of ERPs from normal individuals have played an increasingly important role in our understanding of the mechanisms of attention. This paper focused on studies of specific cognitive subsystems such as visual pathway and attention with ERPs in different kinds of visual stimuli tasks using a 128-channel EEG system. The results have showed all potential amplitude of 19 electrodes varied largely with increasing stimuli task complexity and the P100, N200, P300 are elicited.