Three people have been arrested in connection with the case.
A video of the mother-of-eight sparked massive anger online when it emerged two weeks ago.
Officials first dismissed trafficking claims, but outraged netizens had kept up pressure, with some making daily calls for investigation.
Many of them also raised suspicions about kidnapping and abuse.
Even the hype around the Beijing Olympics has failed to distract people from the issue - a Weibo topic on the woman's plight has received more than 3bn views since the news first emerged.
The woman had been found locked up in a doorless shed outside her home, wearing a thin layer of clothing, in freezing temperatures.
She was taken to hospital after her circumstances were made public by a Chinese vlogger. Officials said she had been diagnosed with schizophrenia.
The case has sparked national furore in China since it emerged in late January and focused attention on women in rural areas and bride trafficking.