Students translated the final Harry Potter book hours after its publication and months ahead of the official Chinese version, state media reports.
Many Chinese Potter fans have already bought the English version
The first Chinese version of Harry Potter and the Deathly Hallows appeared on the internet on 21 July, the day of the English version's global release.
China Daily quoted blogs saying fans "worked in teams and round the clock, eating nothing but instant noodles".
The official Chinese print version is due to be published in October.
The local students added notices to internet editions stating that translations were not for commercial use - to avoid the threat of copyright infringement charges.
"We translated the book because we love Harry, and we do not intend to use it for commercial purposes," the notices said.
About 11 million copies of the novel were sold in the initial 24 hours
But Chinese publishers fear it could lead to counterfeit books, in a country where piracy is rife.
China Daily reported that teenagers on their summer holidays had purchased English-language copies of the book as soon as they hit the shelves last month, and began translating.
A French teenager was recently arrested for publishing his own complete translation of the Deathly Hallows, but will not be prosecuted.
He told police that he had not sought to make money from his unauthorised translation, which appeared within a few days of the official English-language version's global release.
The French-language edition is also due to be published in October.
The seventh instalment of the Potter saga is the fastest-selling book in history, with some 11 million English-language copies being sold within the first 24 hours of publication.