Abstract: The theory of pragmatic identity suggests that the utterer's identity can influence the choice of utterances, and in interaction, speakers can also construct pragmatic identities dynamically through making linguistic choices at different levels.As an important communication strategy, reported speech is frequently employed in courtroom discourses.Taking transcribed texts of 26 authentic criminal cases as data, this paper aims to analyze the linguistic features of reported speech by the prosecutor under his institutional identities and the construction of pragmatic identities in interaction through the use of reported speech of different types and their prosodic features.The findings suggest that, under the institutional identities as the attorney, court prosecutor and inquisitor, sources and contents of reported speeches are different.The prosecutor can also construct pragmatic identities as law practitioner, summary presenter, information confirmer or topic initiator to realize his communicative intention through the strategic use of reported speech and prosodic features of the reported speech.