Deniability is a feature that aims at protecting the privacy of the protocol participants in the key establishment protocols.Currently all the previous researches about deniability in group key establishment protocols were based on the Random Oracle assumption.In this paper,the authors gives a deniable group key establishment protocol without Random Oracle along with its security analysis and deniability analysis.All the proofs are done in Standard Model.The author hopes that the work in this paper could be helpful for the research on the anlysis of the various security features of the group key establishment protocols and the proof in this paper could be helpful for the security analysis of other key establishment protocols.