Chiranuch Premchaiporn, a Web manager, was accused of failing to quickly delete posts made by others on Prachatai, an online forum, in 2010.
She denied the charges and said that she cooperated with government requests to remove offensive postings.
She could face a 20-year prison sentence, but her trial has been delayed until February 2012.
Under Thailand’s cybercrime law, website administrators can be held liable for hosting illegal content, including material that undermines national security.