We investigated the processing of self-related information under the prime paradigm using event-related potentials (ERPs) to provide evidence for implicit self-positivity bias in Chinese individuals. Reaction times and ERPs were recorded when participants made positive/negative emotional judgments to personality-trait adjectives about themselves or others. Faster responses occurred to self-related positive adjectives and other-related negative adjectives, indicating implicit self-positivity bias at the behavioral level. ERPs showed an interaction between prime and emotion at the P300 amplitude, with larger P300 amplitudes for words within the self-positivity bias, indicating that self-related information occupied more attentional resources. Larger N400 amplitudes elicited by words that were inconsistent with the self-positivity bias, suggesting that accessing non-self-relevant information is more difficult than self-relevant information. Thus, P300 and N400 could be used as neuro-indexes of the implicit self-positivity bias.