Xu, 40, who had been under detention since July, was tried Wednesday in a people's intermediary court in Beijing on charges of "assembling a crowd to disrupt order in a public place." His trial is to be followed by that of at least six other activists.
Speaking to CNN, Xu lawyer Zhang Qinfang quoted prosecutors as saying his client "gathered a crowd to disturb public order" after a series of small protests calling on officials to publicly declare their assets. The charge relates to incidents in 2012 and last year.
It was unclear when the verdict would come but Zhang told CNN Xu could be sent to prison for five years if convicted, which Zhang said is likely because of the political nature of the case. The case has attracted much international attention.
Through his New Citizens Movement, Xu and other activists had also been advocating other issues such as greater rule of law and fairer access to education.
Zhang said Xu at the trial tried to read a prepared statement to explain the objectives of his movement but the judge interrupted when Xu said top leaders should be transparent about their assets.
"Calling on officials to reveal their assets was our effort to promote the country's anti-graft system," Xu said before he was removed from the courtroom, Zhang said.
CNN said Chinese authorities had treated roughly international media covering the case. The report said its crew was stopped from approaching the court house and its Beijing correspondent was kicked, pushed and punched by security people before being forced into a van and driven away.
It had been hoped when Xi Jinping became president last year he would promote free speech.
The Washington Post also said Chinese authorities did not permit foreign journalists to report from nearby streets and barred diplomats from attending the trial.