It took firefighters about an hour to free the 25-year-old man from the narrow vent leading to the bathroom of the apartment in Chongqing city.
Neighbours alerted police after finding the man dangling from the opening, 'Global Times' reported.
Initially the man tried to pass himself off as a relative of the apartment's owner looking to pick up things he had left inside.
The man, who weighs about 50 kilogrammes, told police that his slender physique had come in handy during similar break-ins in the past, the report said.