What is the function of chorus in play "Antigone"?
The Chorus acts as a narrator and as a body that suggests how the audience should react to the events of the play. The Chorus can also interact directly with the characters of the play and in doing so, influence how the events transpire.
In Antigone they act as the observers or townspeople of Thebes. They also provide the prologue and epilogue which set up the boundaries of the actions about to unfold for the viewer of the play.
One slight comparison I would make is to that of Bottom the Weaver in A Midsummer Night's Dream. Just as Bottom is betwixt and between the realm of reality and that of the land of the fairies and the mystical, so is the Chorus. The Chorus is betwixt and between the realm of the play, and that of spectator. Bottom and the Chorus serve as a guide through the written word of the author.
The chorus is the voice of the people, it warns of impending evil, it rejoices in an good; it wails aloud in grief. It sees mankind as the puppets of the Gods. The chorus represents the 'crowd' the 'judges' of the characters on stage, commentators and passers of opinion. Its role is to comment on the themes and react as perhaps the audience should, guiding the audience toward understanding. Through the chorus Creon comes to understand that he is wrong and God is superior to himself, that he is merely a human in a world far greater than the walls of his kingdom.One role of the play is to comment on the human condition and this is provided by the chorus. At first the chorus may appear weak, it accommodates itself to the tyranny of Creon, it does not intervene on the side of Antigone; it is initially a submissive chorus. However this makes Antigone stand alone, necessary for the play and showing the irresistible nature of the king's command.
In Greek theatre the chorus would often dress like the chief actor, unless that was a woman. But in 'Antigone' the chorus would be men to show the isolation of Antigone against a background of grief.