A man has been charged with headbutting a police officer at Sydney's Big Day Out music festival, leaving him with a broken nose.

The officer was allegedly assaulted while attempting to restrain the man after he jumped a barrier to enter the Sydney Showgrounds about 7pm (AEDT) on Friday.

The injured officer was taken to Concord Hospital, where it is anticipated he will require surgery, police say.

A 23-year-old man was arrested and taken to Auburn Police Station, where he was charged with causing grievous bodily harm with intent to resist arrest.

He was granted conditional bail to appear in Burwood Local Court on February 12.