A Sydney man accused of travelling to Syria to fight for a terrorist group has pleaded guilty to one of the charges laid against him.

Belal Betka, 26, was arrested at a house he shared with his mother at Mount Lewis in Sydney's south-west in December 2017, and became the first Australian citizen charged under Federal foreign incursion laws.

The offence carries a maximum penalty of life in prison.

Police said he travelled to Syria's al-Raqqa province in 2015 at a time when it was declared by the Australian government as an area where a terrorist group was engaging in hostile activity.

This declaration was revoked in late 2017.

Authorities said that between March and July 2015, Belal entered a conflict, associated with terrorists, manned a checkpoint and fired a weapon with the intention of overthrowing the Syrian Government.

Wearing prison greens, the 26 year old appeared in the NSW Supreme Court via video link from a Goulburn jail.

Betka pleaded guilty to one of the charges laid against him.

The court heard there had been talks between Federal prosecutors and Betka's lawyers about another charge he is facing under incursion laws.

He indicated he did not yet want to enter a plea to the charge.

Justice Elizabeth Fullerton noted that the other charge may end up going to trial.

The matter will return to court in August.