Ahmad Qasem was sentenced to five years in jail but his term was commuted to three years.
"The charge is belonging to a group that seeks to split territory off from Syria," said Faisal Badr, a lawyer who attended Sunday's court session.
Qasem belonged to the banned Kurdish Democratic Progressive Party in Syria and has been in custody for 30 months, Badr said.
He questioned the validity of the ruling because it was made by a court formed under an emergency law introduced in 1963.
Syrian human rights activists have sought an end to the emergency law, but the government links the law to the country's war with Israel and not to internal affairs.
Several banned Kurdish political groups in Syria, which has an estimated two million Kurds, demand the right to teach their language.
They also demand citizenship, which is required for state education and employment, for about 200,000 Kurds classified as stateless based on a 1962 survey.
"Ahmad Qasem was sentenced to five years in jail but the term was commuted to three years. The charge is belonging to a group that seeks to split territory off from Syria"
Three Kurds belonging to another banned faction were sentenced to 30 months in jail in May on similar separatist charges.
Later on Sunday, riot police dispersed a demonstration by hundreds of Syrian Kurds in the northeastern town of Kameshli, residents said.
The demonstration was organised by two other banned Kurdish parties, Yikiti and Azadi Kurdish Party in Syria.
Deadly football brawl
A Kurdish politician in Damascus said thousands had taken part in the peaceful demonstration seeking an end to what he described as extraordinary treatment of Syrian Kurds. He said several Kurds were injured.
"They used tear gas after some of the demonstrators fired shots toward the police," said a non-Kurd resident by telephone from the town.
Al-Assad pardoned 312 Kurds
accused of violence last year
Officials were not immediately available for comment.
In 2004, about 30 people including policemen were killed in Kameshli when a brawl after a football match triggered riots and clashes with the police.
President Bashar al-Assad pardoned 312 Syrian Kurds accused of taking part in the violence in March.