Enhancing reputation mechanism’s capability of aggregating reputation information effectively is the foundation of a successful reputation system. Current reputation systems based on localized reputation information cannot process such strategic recommendations as correlative and collusive ratings. Furthermore there exists unfairness to blameless peers in these models. Therefore, a Credibility Enhanced Reputation mechanism CERep is presented. In CERep, a peer uses its experiences to compute the direct trust valuation which contains direct trust value and level of confidence about this value, then a reputation-based trust valuation scheme and recommendation credibility computation model is proposed. Moreover, the strategies used for implementing the reputation mechanism are also discussed. Theoretical analysis and simulation show that CERep reputation mechanism proposed can help peers effectively detect dishonest recommendations in a variety of scenarios where more complex malicious strategies are introduced, and achieve a more accurate trust valuation and fair evaluation of recommendations.