P300 event-related brain potential (ERP) measures are affected by target stimulus probability, the number of no-go targets preceding the target in the stimulus sequence structure, and inter stimulus interval (ISI). Each of these factors contributes to the target-to-target interval (TTI), which also has been found to affect P300. Here we combined the cue-target paradigm with the task to investigate when the central cue could completely predicts the cue-target interval (CTI) (600ms or 1800ms), which induced totally temporally endogenous attention, whether the cue-target interval (the time between cue-offset and target-onset) could affect the amplitude or latency of P300 component or not. The results showed that the latency of P300 would not change in short (600ms) or long (1800ms) cue-target intervals conditions, which indicating the temporally endogenous attention had no effect on the time processing of the target, even the temporal cue could predict when the target appeared. However, the mean amplitude of P300 (from 300ms to 600ms, after target onset) increased with the increasing cue-target interval, which might support that the temporal factor that was either target-target interval or cue-target interval, might determine the amplitude of P300.