A man accused of aiding and abetting the arson of Old Parliament House, which caused millions of dollars worth of damage to the historic building, has been committed to trial in the ACT Supreme Court.

Bruce Shillingsworth Jr, 30, has been accused of being a ringleader of the group.

The building was damaged by two fires started at the front doors in December, with the most damage done in the second instance.

The repair bill was put at about $5 million, with most of the damage inside the building caused by smoke and water, and the building was closed to the public until April. 

Mr Shillingsworth Jr has pleaded not guilty to the charges of aiding and abetting arson, and damaging Commonwealth property.

He appeared briefly in the ACT Magistrates Court today, when he was committed for trial.

Police allege he helped a second man, Nicholas Reed, by clearing the way and directing Mr Reed as he carried hot coals to the doors.

Mr Reed has also been charged with arson and has already been committed for trial.

Both are due to appear in the ACT Supreme Court next month, but no trials are likely until next year.

Several others have also been charged over the incident.