Police took away Huang Zerong, better known as Tieliu, on Sunday and issued a notice later that he had been detained on the vague charge of causing trouble, his wife, Ren Hengfang, said.
She said police also detained Huang's medical caregiver on the same charge on the same day. There was no explanation of why the caregiver was detained.
Beijing police did not immediately respond to a request for comment.
Huang's wife said he recently wrote several articles criticizing Liu Yunshan, a member of the powerful Politburo Standing Committee and the ruling Communist Party's propaganda chief, for tightening controls over the news media.
China's leadership has become less intolerant of criticism, and authorities are increasingly using coercion and detentions to suppress dissent.