Mustakim Jaman, 23, of Hudson Road, Southsea, has been charged under section five of the Terrorism Act 2006.
He is the brother of Ifthekar Jaman, who was killed in Syria in December.
Mr Jaman is due at Westminster Magistrates' Court on Monday. Another brother, Tuhin Shahensha, 26, has also been charged with terrorism offences.
Mr Shahensha, also of Hudson Road, appeared in court on Friday accused of planning to fight in Syria. He is due to appear at the Old Bailey on 14 November.
The two men, of Hudson Road, Southsea, were arrested along with a number of other people in Hampshire and London on 14 October by the South East Counter Terrorism Unit (SECTU).
A 57-year-old man and a 48-year-old woman have been released on bail.
A 23-year-old woman from Farnborough and a 29-year-old woman from Greenwich, south-east London, have been released without charge.
The brother of a Portsmouth man killed while fighting for Islamic State (IS) in Syria has been charged with preparing terrorist acts.