A body found in an abandoned Shanghai University campus building on Tuesday is thought to be that of a graduate student who was reported missing a month ago, the university said.

Shanghai University said on its micro blog that the male student had enrolled at the university this year, and it offered condolences to his family and friends.

Police in Shanghai's Jia-ding's district said on their micro blog on Tuesday night that they had ruled out murder, adding that an investigation into the death is ongoing.

Beijing News reported that the student's body was found hanging on the door frame in the second floor of the abandoned building on Tuesday morning.

The body was discovered by a pair of young lovers who were going inside the building "on an adventure". The police first received news of a missing Shanghai University student from family members on Nov 17.

"The body was rotten and it was very difficult to identify the person," the report quoted an unnamed police officer with the Jiading police. The officer said a DNA test will be necessary to identify the body.

The student, surnamed Li, had been missing since Nov 12, and his family and girlfriend had posted notices on social media in an effort to find him.

His family had come from their home in Northeast China to try to find him after his girlfriend notified them that he was missing.

"The DNA result is not out yet. We still hope it is not him," Li's cousin said.

The student had no arguments with family members or his girlfriend before he disappeared, his cousin said.

An only child, Li was open and easygoing and got along well with his friends, the cousin said. "The fact is simply unacceptable to us," she said.