Pravit Rojanaphruk, a senior writer for the local news outlet Khaosod English, told AFP he faces up to 14 years in prison over two cases filed by police.
The first is linked to his Facebook posts from February 2016 that criticised a junta-drafted constitution.
The second case concerns Facebook posts from last month that criticised junta leader Prayut Chan-O-Cha's handling of floods and the trial of ousted premier Yingluck Shinawatra, whose elected government was toppled in a 2014 military coup.
"The law is being used to silence criticism on social media."
Also Read
The writer also faces charges under the Computer Crime Act -- another tough law used by the junta to stamp out online dissent.
Since the coup Pravit has twice been detained by soldiers for "attitude adjustment" sessions.
But he has continued his criticism of the military regime, detailing the surge in prosecutions of government and monarchy critics.
Last month he was named winner of a international press freedom award from the Committee to Protect Journalists.
Tensions are rising before the verdict in Yingluck's negligence trial on August 25.
The former premier may face up to a decade in jail if found guilty. Any harsh sentence could reignite conflict between her fervent supporters and the regime, which has suppressed all political activities for the past three years.
The junta has defended its clampdown as an attempt to heal bitter political rivalries which have fuelled a decade of unrest.
The siblings dominate national elections but are loathed by a military-allied elite, which accuses them of corruption and costly populist handouts.
Disclaimer: No Business Standard Journalist was involved in creation of this content