Mo Shaoping, who is representing activist Huang Qi, said the postponement came after he protested that the original starting time of Tuesday morning — announced only on Monday — left him less than 24 hours to study the indictment and build a defense against the charge of possessing state secrets.
Mo said the judge has yet to fix the later date.
Earlier Monday, Mo, one of China's best-known human rights lawyers, had said that the sudden announcement of the trial date was illegal and accused the court of "intentionally creating difficulties." According to Mo, rules demand that lawyers be informed of a trial date at least three days in advance.
Telephones at the court in Chengdu, Sichuan's capital, rang unanswered Monday.
Huang had posted articles on his Web site 64Tianwang.com criticizing the government's response to last May 12's magnitude-7.9 temblor after visiting affected areas and meeting parents who lost their children in the collapse of badly built schools.
Public complaints by parents who blamed corruption and shoddy construction for school collapses have since became an extremely sensitive issue.
Human rights groups said Huang was forcibly taken away by three unknown men on June 10 and police informed his mother six days later that he had been detained.
China's Communist leaders often use ill-defined state secrets charges to clamp down on dissent and send activists to prison.
Earlier this decade, Huang, 45, served a five-year prison sentence on subversion charges linked to politically sensitive articles posted on his Web site.
Since his release in 2005, Huang has supported a wide range of causes from aiding families of those killed in the 1989 military crackdown on pro-democracy protests in Beijing, to publicizing the complaints of farmers involved in land disputes with authorities.