He was one of the founders of the NGO Open Constitution Initiative and an active rights lawyer in China who campaigned against corruption[1] and helped those underprivileged.

[2] He was detained again on February 15, 2020, in the southern city of Guangzhou after two months in hiding, for his participation in a meeting of rights activists and lawyers in Xiamen in December 2019 in which "democratic transition in China" was discussed.

[10] Unlike other human rights activists, Xu firmly and carefully pushed his calls for political change and social justice in existing laws, and his group has been regarded as relatively cautious and conservative.

[17][19] The Australian newspaper The Age reported that the release of Xu, Zhuang and another Chinese dissident, Ilham Tohti, was in part due to pressure on Beijing from the administration of American President Barack Obama.

Xu and his lawyer Zhang Qingfang remained silent throughout the trial (except for his closing statement) to protest the violation of basic legal procedure.

Xu's closing statement was cut short by the judge, but the text was circulated on the internet[22] and raised tremendous support.

[24] Xu and other human rights activists were wanted by police for their participation in a meeting in Xiamen on December 13, 2019[25][26] where "democratic transition in China" was discussed.

[8] In February 2020, while in hiding, through postings on social media, Xu publicly asked Chinese Communist Party general secretary Xi Jinping to resign, for what he described as an obvious inability to handle the COVID-19 pandemic.

[28] In November 2021, Liang Xiaojun, the lawyer of Xu, had his license cancelled by authorities, with the notification letter citing his online support for Falun Gong and "vilifying" the Chinese constitution and laws.