Trust and reputation are important decision-making factors in cooperative computing systems. It is a fundamental but challenging task for reputation systems to estimate entity's reputation accurately and efficiently in distributed environment. We propose EntityTrust, a global reputation mechanism in cooperative computing systems. EntityTrust introduces a new direct feedback metrics to reflect the dynamic feature of trust. Besides that, an entity's feedback credibility can affect its reputation in a direct way. Experimental results show that EntityTrust can improve the accuracy and efficiency of evaluation for global reputation. Moreover, it can effectively combat malicious behaviors presented in the cooperative communities.